@string{brics =	"{BRICS}"}
@string{daimi =	"Department of Computer Science, University of Aarhus"}
@string{iesd  =	"Department of Computer Science, Institute
of Electronic Systems, Aalborg University"}
@string{rs    =	"Research Series"}
@string{ns    =	"Notes Series"}
@string{ls    =	"Lecture Series"}
@string{ds    =	"Dissertation Series"}

@techreport{BRICS-RS-02-53,
author = 	 "Danvy, Olivier",
title = 	 "A Lambda-Revelation of the {SECD} Machine",
institution =  brics,
year = 	 2003,
type = 	 rs,
number = 	 "RS-02-53",
month = 	 dec,
note = 	 "15~pp. Superseeded by the BRICS report
abstract = 	 "We present a simple inter-derivation between
lambda-interpreters, i.e., evaluation functions
for lambda-terms, and abstract reduction
machines for the lambda-calculus, i.e.,
transition functions. The two key derivation
steps are the CPS transformation and Reynolds's
defunctionalization. By transforming the
interpreter into continuation-passing style
(CPS), its flow of control is made manifest as
a continuation. By defunctionalizing this
continuation, the flow of control is
materialized as a first-order data
structure.\bibpar

The derivation applies not merely to connect
independently known lambda-interpreters and
abstract machines, it also applies to construct
the abstract machine corresponding to a
lambda-interpreter and to construct the
lambda-interpreter corresponding to an abstract
machine. In this article, we treat in detail
the canonical example of Landin's SECD machine
and we reveal its denotational content: the
meaning of an expression is a partial
endo-function from a stack of intermediate
results and an environment to a new stack of
intermediate results and an environment. The
corresponding lambda-interpreter is
unconventional because (1) it uses a control
delimiter to evaluate the body of each
lambda-abstraction and (2) it assumes the
environment to be managed in a callee-save
fashion instead of in the usual caller-save
fashion",
}
@techreport{BRICS-RS-02-52,
author = 	 "Danvy, Olivier",
title = 	 "A New One-Pass Transformation into Monadic
Normal Form",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-52",
month = 	 dec,
note = 	 "16~pp. Appears in " # lncs2622 # ", pages
77--89",
abstract = 	 "We present a translation from the
call-by-value lambda-calculus to monadic normal
forms that includes short-cut boolean
evaluation. The translation is higher-order,
operates in one pass, duplicates no code,
generates no chains of thunks, and is properly
tail recursive. It makes a crucial use of
symbolic computation at translation time",
}
@techreport{BRICS-RS-02-51,
author = 	 "Brodal, Gerth St{\o}lting and Fagerberg, Rolf
and {\"O}stlin, Anna and Pedersen, Christian N.
S. and Rao, S. Srinivasa",
title = 	 "Computing Refined Buneman Trees in Cubic
Time",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-51",
month = 	 dec,
note = 	 "14~pp. Appears in " # lncs2812 # ", pages
259--270",
abstract = 	 "Reconstructing the evolutionary tree for a set
of $n$~species based on pairwise distances
between the species is a fundamental problem in
bioinformatics. Neighbor joining is a popular
distance based tree reconstruction method. It
always proposes fully resolved binary trees
despite missing evidence in the underlying
distance data. Distance based methods based on
the theory of Buneman trees and refined Buneman
trees avoid this problem by only proposing
evolutionary trees whose edges satisfy a number
of constraints. These trees might not be fully
resolved but there is strong combinatorial
evidence for each proposed edge. The currently
best algorithm for computing the refined
Buneman tree from a given distance measure has
a running time of $O(n^5)$ and a space
consumption of $O(n^4)$. In this paper, we
present an algorithm with running time~$O(n^3)$
and space consumption~$O(n^2)$",
}
@techreport{BRICS-RS-02-50,
author = 	 "Hansen, Kristoffer Arnsfelt and Miltersen,
Peter Bro and Vinay, V.",
title = 	 "Circuits on Cylinders",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-50",
month = 	 dec,
note = 	 "16~pp",
abstract = 	 "We consider the computational power of
constant width polynomial size cylindrical
circuits and nondeterministic branching
programs. We show that every function computed
by a ${{\bf\Pi}_2 \circ{\rm\bf MOD} \circ{\rm \bf AC}^0}$ circuit can also be computed by a
constant width polynomial size cylindrical
nondeterministic branching program (or
cylindrical circuit) and that every function
computed by a constant width polynomial size
cylindrical circuit belongs to ${\mbox{\rm\bf ACC}}^0$",
}

@techreport{BRICS-RS-02-49,
author = 	 "Nygaard, Mikkel and Winskel, Glynn",
title = 	 "{HOPLA}---{A} Higher-Order Process Language",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-49",
month = 	 dec,
note = 	 "18~pp. Appears in " # lncs2421 # ", pages
434--448",
abstract = 	 "A small but powerful language for higher-order
nondeterministic processes is introduced. Its
roots in a linear domain theory for concurrency
are sketched though for the most part it lends
itself to a more operational account. The
language can be viewed as an extension of the
lambda calculus with a prefixed sum'', in
which types express the form of computation
path of which a process is capable. Its
operational semantics, bisimulation, congruence
properties and expressive power are explored;
in particular, it is shown how it can directly
encode process languages such as CCS, CCS with
process passing, and mobile ambients with
public names",
}

@techreport{BRICS-RS-02-48,
author = 	 "Nygaard, Mikkel and Winskel, Glynn",
title = 	 "Linearity in Process Languages",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-48",
month = 	 dec,
note = 	 "27~pp. Appears in " # lics17 # ", pages
433--446",
abstract = 	 "The meaning and mathematical consequences of
linearity (managing without a presumed ability
to copy) are studied for a path-based model of
processes which is also a model of
affine-linear logic. This connection yields an
af\-fine-linear language for processes,
automatically respecting open-map bisimulation,
in which a range of process operations can be
expressed. An operational semantics is provided
for the tensor fragment of the language.
Different ways to make assemblies of processes
lead to different choices of exponential, some
of which respect bisimulation",
}

@techreport{BRICS-RS-02-47,
author = 	 "{\'E}sik, Zolt{\'a}n",
title = 	 "Extended Temporal Logic on Finite Words and
Wreath Product of Monoids with Distinguished
Generators",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-47",
month = 	 dec,
note = 	 "16~pp. Appears in " # lncs2450 # ", pages 43--48",
abstract = 	 "We associate a modal operator with each
language belonging to a given class of regular
languages and use the (reverse) wreath product
of monoids with distinguished generators to
characterize the expressive power of the
resulting logic",
}

@techreport{BRICS-RS-02-46,
author = 	 "{\'E}sik, Zolt{\'a}n and Lei{\ss}, Hans",
title = 	 "{G}reibach Normal Form in Algebraically
Complete Semirings",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-46",
month = 	 dec,
note = 	 "43~pp. An extended abstract appears in " #
lncs2471 # ", pages 135--150",
keywords = 	 "Greibach normal form, context-free languages,
pre-fixed-point induction, equational theory,
Conway semiring, Kleene algebra, algebraically
complete semiring",
abstract = 	 "We give inequational and equational axioms for
semirings with a fixed-point operator and
formally develop a fragment of the theory of
context-free languages. In particular, we show
that Greibach's normal form theorem depends
only on a few equational properties of least
pre-fixed-points in semirings, and elimination
of chain- and deletion rules depend on their
inequational properties (and the idempotency of
addition). It follows that these normal form
theorems also hold in non-continuous semirings
having enough fixed-points",
}

@techreport{BRICS-RS-02-45,
author = 	 "Byskov, Jesper Makholm",
title = 	 "Chromatic Number in Time $O(2.4023^n)$ Using
Maximal Independent Sets",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-45",
month = 	 dec,
note = 	 "6~pp",
abstract = 	 "In this paper we improve an algorithm by
Eppstein (2001) for finding the chromatic
number of a graph. We modify the algorithm
slightly, and by using a bound on the number of
maximal independent sets of size~$k$ from our
recent paper (2003), we prove that the running
time is $O(2.4023^n)$. Eppstein's algorithm
runs in time $O(2.4150^n)$. The space usage for
both algorithms is $O(2^n)$",
}

@techreport{BRICS-RS-02-44,
author = 	 "{\'E}sik, Zolt{\'a}n and N{\'e}meth,
Zolt{\'a}n L.",
title = 	 "Higher Dimensional Automata",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-24",
month = 	 nov,
note = 	 "32~pp. A preliminary version appears under the
title {\em Automata on Series-Parallel
Biposets\/} in " # lncs2295 # ", pages
217--227. This report supersedes the earlier
BRICS report RS-01-24",
abstract = 	 "We provide the basics of a 2-dimensional
theory of automata on series-parallel biposets.
We define recognizable, regular and rational
sets of series-parallel biposets and study
their relationship. Moreover, we relate these
classes to languages of series-parallel
biposets definable in monadic second-order
logic",
}

@techreport{BRICS-RS-02-43,
author = 	 "Christiansen, Mikkel and Fleury, Emmanuel",
title = 	 "Using {IDD}s for Packet Filtering",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-43",
month = 	 oct,
note = 	 "25~pp",
abstract = 	 "Firewalls are one of the key technologies used
to control the traffic going in and out of a
network. A central feature of the firewall is
the {\em packet filter}. In this paper, we
propose a complete framework for packet
classification. Through two applications we
demonstrate that both performance and security
can be improved.\bibpar

We show that a traditional ordered rule set can
always be expressed as a first-order logic
formula on integer variables. Moreover, we
emphasize that, with such specification, the
packet filtering problem is known to be
constant time ($O(1)$). We propose to represent
the first-order logic formula as {\em Interval
Decision Diagrams}. This structure has several
advantages. First, the algorithm for removing
redundancy and unnecessary tests is very
simple. Secondly, it allows us to handle
integer variables which makes it efficient on a
generic CPUs. And, finally, we introduce an
extension of IDDs called {\em Multi-Terminal
Interval Decision Diagrams} in order to deal
with any number of policies.\bibpar

In matter of efficiency, we evaluate the
performance our framework through a prototype
toolkit composed by a {\em compiler} and a {\em
packet filter}. The results of the experiments
shows that this method is efficient in terms of
CPU usage and has a low storage
requirements.\bibpar

Finally, we outline a tool, called {\em Network
Access Verifier}. This tool demonstrates how
the IDD representation can be used for
verifying access properties of a network. In
total, potentially improving the security of a
network",
}

@techreport{BRICS-RS-02-42,
author = 	 "Aceto, Luca and Hansen, Jens Alsted and
Ing{\'o}lfsd{\'o}ttir, Anna and Johnsen, Jacob
and Knudsen, John",
title = 	 "Checking Consistency of Pedigree Information
is {NP}-complete (Preliminary Report)",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-42",
month = 	 oct,
note = 	 "16~pp. Superseeded by RS-03-17",
abstract = 	 "{Consistency checking} is a fundamental
computational problem in genetics. Given a
pedigree and information on the genotypes of
some of the individuals in it, the aim of
consistency checking is to determine whether
these data are consistent with the classic
Mendelian laws of inheritance. This problem
arose originally from the geneticists' need to
filter their input data from erroneous
information, and is well motivated from both a
biological and a sociological viewpoint. This
paper shows that consistency checking is
NP-complete, even in the presence of three
alleles. Several other results on the
computational complexity of problems from
genetics that are related to consistency
checking are also offered. In particular, it is
shown that checking the consistency of
pedigrees over two alleles can be done in
polynomial time",
}
@techreport{BRICS-RS-02-41,
author = 	 "Bloom, Stephen L. and {\'E}sik, Zolt{\'a}n",
title = 	 "Axiomatizing Omega and Omega-op Powers of
Words",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-41",
month = 	 oct,
note = 	 "16~pp",
abstract = 	 "In 1978, Courcelle asked for a complete set of
axioms and rules for the equational theory of
(discrete regular) words equipped with the
operations of product, omega power and omega-op
power. In this paper we find a simple set of
equations and prove they are complete.
Moreover, we show that the equational theory is
decidable in polynomial time",
}

@techreport{BRICS-RS-02-40,
author = 	 "Aceto, Luca and Fokkink, Willem Jan and
Ing{\'o}lfsd{\'o}ttir, Anna",
title = 	 "A Note on an Expressiveness Hierarchy for
Multi-exit Iteration",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-40",
month = 	 sep,
note = 	 "8~pp. Appears in {\em Information Processing
Letters}, Elsevier, 87(1):17--23, 2003.",
abstract = 	 "Multi-exit iteration is a generalization of
the standard binary Kleene star operation that
allows for the specification of agents that, up
to bisimulation equivalence, are solutions of
systems of recursion equations of the form
\begin{eqnarray*} X_1 & \stackrel{\mbox{\tiny
def}}{=} & P_1 X_2 + Q_1 \\
& \vdots& \\
X_n & \stackrel{\mbox{\tiny def}}{=} & P_n X_1
+ Q_n \end{eqnarray*} where $n$ is a positive
integer, and the $P_i$ and the $Q_i$ are
process terms. The addition of multi-exit
iteration to Basic Process Algebra (BPA) yields
a more expressive language than that obtained
by augmenting BPA with the standard binary
Kleene star. This note offers an expressiveness
hierarchy, modulo bisimulation equivalence, for
the family of multi-exit iteration operators
proposed by Bergstra, Bethke and Ponse",
}
@techreport{BRICS-RS-02-39,
author = 	 "Bloom, Stephen L. and {\'E}sik, Zolt{\'a}n",
title = 	 "Some Remarks on Regular Words",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-39",
month = 	 sep,
note = 	 "27~pp",
abstract = 	 "In the late 1970's, Courcelle introduced the
class of arrangements'', or labeled linear
ordered sets, here called just words''. He
singled out those words which are solutions of
finite systems of fixed point equations
involving finite words, which we call the
regular words''. The current paper contains
some new descriptions of this class of words
related to properties of regular sets of binary
strings, and uses finite automata to decide
various natural questions concerning these
words. In particular we show that a countable
word is regular iff it can be defined on an
ordinary regular language (which can be chosen
to be a prefix code) ordered by the
lexicographical order such that the labeling
function satisfies a regularity condition.
Those regular words whose underlying order is
discrete'' or scattered'' are characterized
in several ways",
}

@techreport{BRICS-RS-02-38,
author = 	 "Varacca, Daniele",
title = 	 "The Powerdomain of Indexed Valuations",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-38",
month = 	 sep,
note = 	 "54~pp. Short version appears in " # lics17 #
", pages~299--308",
abstract = 	 "This paper is about combining nondeterminism
and probabilities. We study this phenomenon
from a domain theoretic point of view. In
domain theory, nondeterminism is modeled using
the notion of powerdomain, while probability is
modeled using the powerdomain of valuations.
Those two functors do not combine well, as they
are. We define the notion of powerdomain of
indexed valuations, which can be combined
nicely with the usual nondeterministic
powerdomain. We show an equational
characterization of our construction. Finally
we discuss the computational meaning of indexed
valuations, and we show how they can be used,
by giving a denotational semantics of a simple
imperative language",
}

@techreport{BRICS-RS-02-37,
author = 	 "Ager, Mads Sig and Danvy, Olivier and
Goldberg, Mayer",
title = 	 "A Symmetric Approach to Compilation and
Decompilation",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-37",
month = 	 aug,
note = 	 "45~pp. Appears in " # lncs2566 # ", pages
296--331",
abstract = 	 "Just as specializing a source interpreter can
achieve compilation from a source language to a
target language, we observe that specializing a
target interpreter can achieve compilation from
the target language to the source language. In
both cases, the key issue is the choice of
whether to perform an evaluation or to emit
code that represents this evaluation.\bibpar
We substantiate this observation by
specializing two source interpreters and two
target interpreters. We first consider a source
language of arithmetic expressions and a target
language for a stack machine, and then the
lambda-calculus and the SECD-machine language.
In each case, we prove that the
target-to-source compiler is a left inverse of
the source-to-target compiler, i.e., it is a
decompiler.\bibpar
In the context of partial evaluation,
compilation by source-interpreter
specialization is classically referred to as a
Futamura projection. By symmetry, it seems
logical to refer to decompilation by
target-interpreter specialization as a Futamura
embedding",
}

@techreport{BRICS-RS-02-36,
author = 	 "Damian, Daniel and Danvy, Olivier",
title = 	 "{CPS} Transformation of Flow Information, Part
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-36",
month = 	 aug,
note = 	 "9~pp. To appear in the {\em Journal of
Functional Programming}. This report supersedes
the earlier BRICS report RS-01-40",
abstract = 	 "We characterize the impact of a linear $\beta$-reduction on the result of a control-flow
analysis. (By a linear $\beta$-reduction'' we
mean the $\beta$-reduction of a linear $\lambda$-abstraction, i.e., of a $\lambda$-abstraction
whose parameter occurs exactly once in its
body.)\bibpar
As a corollary, we consider the administrative
reductions of a Plotkin-style transformation
into continuation-passing style (CPS), and how
they affect the result of a constraint-based
control-flow analysis and, in particular, the
least element in the space of solutions. We
show that administrative reductions preserve
the least solution. Preservation of least
solutions solves a problem that was left open
in Palsberg and Wand's article CPS
Transformation of Flow Information.''\bibpar
Together, Palsberg and Wand's article and the
present article show how to map in linear time
the least solution of the flow constraints of a
program into the least solution of the flow
constraints of the CPS counterpart of this
program, after administrative reductions.
Furthermore, we show how to CPS transform
control-flow information in one pass",
}

@techreport{BRICS-RS-02-35,
author = 	 "Bouyer, Patricia",
title = 	 "Timed Automata May Cause Some Troubles",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-35",
month = 	 aug,
note = 	 "44~pp",
abstract = 	 "Timed automata are a widely studied model. Its
decidability has been proved using the
so-called region automaton construction. This
construction provides a correct abstraction for
the behaviours of timed automata, but it does
not support a natural implementation and, in
practice, algorithms based on the notion of
zones are implemented using adapted data
structures like DBMs. When we focus on forward
analysis algorithms, the exact computation of
all the successors of the initial
configurations does not always terminate. Thus,
some abstractions are often used to ensure
termination, among which, a widening operator
on zones.\bibpar
In this paper, we study in details this
widening operator and the forward analysis
algorithm that uses it. This algorithm is most
used and implemented in tools like Kronos and
Uppaal. One of our main results is that it is
hopeless to find a forward analysis algorithm,
that uses such a widening operator, and which
is correct. This goes really against what one
could think. We then study in details this
algorithm in the more general framework of
updatable timed automata, a model which has
been introduced as a natural syntactic
extension of classical timed automata. We
describe subclasses of this model for which a
correct widening operator can be found",
}

@techreport{BRICS-RS-02-34,
author = 	 "Rhiger, Morten",
title = 	 "A Foundation for Embedded Languages",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-34",
month = 	 aug,
note = 	 "29~pp. To appear in {\em TOPLAS, ACM
Transactions on Programming Languages and
Systems}",
abstract = 	 "Recent work on embedding object languages into
Haskell use phantom types'' (i.e.,
parameterized types whose parameter does not
occur on the right-hand side of the type
definition) to ensure that the embedded
object-language terms are simply typed. But is
it a safe assumption that {\em only}
simply-typed terms can be represented in
Haskell using phantom types? And conversely,
can {\em all} simply-typed terms be represented
in Haskell under the restrictions imposed by
phantom types? In this article we investigate
the conditions under which these assumptions
are true: We show that these questions can be
answered affirmatively for an idealized
Haskell-like language and discuss to which
extent Haskell can be used as a meta-language",
}

@techreport{BRICS-RS-02-33,
author = 	 "Balat, Vincent and Danvy, Olivier",
title = 	 "Memoization in Type-Directed Partial
Evaluation",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-33",
month = 	 jul,
note = 	 "18~pp. Appears in " # lncs2487 # ", pages
78--92",
abstract = 	 "We use a code generator---type-directed
partial evaluation---to verify conversions
between isomorphic types, or more precisely to
verify that a composite function is the
identity function at some complicated type. A
typed functional language such as ML provides a
natural support to express the functions and
type-directed partial evaluation provides a
convenient setting to obtain the normal form of
their composition. However, off-the-shelf
type-directed partial evaluation turns out to
yield gigantic normal forms.\bibpar

We identify that this gigantism is due to
redundancies, and that these redundancies
originate in the handling of sums, which uses
delimited continuations. We successfully
eliminate these redundancies by extending
type-directed partial evaluation with
memoization capabilities. The result only works
for pure functional programs, but it provides
an unexpected use of code generation and it
yields orders-of-magnitude improvements both in
time and in space for type isomorphisms.",
}

@techreport{BRICS-RS-02-32,
author = 	 "Ager, Mads Sig and Danvy, Olivier and Rohde,
Henning Korsholm",
title = 	 "On Obtaining {K}nuth, {M}orris, and {P}ratt's
String Matcher by Partial Evaluation",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-32",
month = 	 jul,
note = 	 "43~pp. Appears in " # acmasiapepm02 # ", pages
32--46",
abstract = 	 "We present the first formal proof that partial
evaluation of a quadratic string matcher can
yield the precise behaviour of Knuth, Morris,
and Pratt's linear string matcher.\bibpar

Obtaining a KMP-like string matcher is a
canonical example of partial evaluation:
starting from the naive, quadratic program
checking whether a pattern occurs in a text,
one ensures that backtracking can be performed
at partial-evaluation time (a binding-time
shift that yields a staged string matcher);
specializing the resulting staged program
yields residual programs that do not back up on
the text, a la KMP. We are not aware, however,
of any formal proof that partial evaluation of
a staged string matcher precisely yields the
KMP string matcher, or in fact any other
specific string matcher.\bibpar

In this article, we present a staged string
matcher and we formally prove that it performs
the same sequence of comparisons between
pattern and text as the KMP string matcher. To
this end, we operationally specify each of the
programming languages in which the matchers are
written, and we formalize each sequence of
comparisons with a trace semantics. We also
state the (mild) conditions under which
specializing the staged string matcher with
respect to a pattern string provably yields a
specialized string matcher whose size is
proportional to the length of this pattern
string and whose time complexity is
proportional to the length of the text string.
Finally, we show how tabulating one of the
functions in this staged string matcher gives
rise to the next' table of the original KMP
algorithm.\bibpar

The method scales for obtaining other linear
string matchers, be they known or new",
}

@techreport{BRICS-RS-02-31,
author = 	 "Kohlenbach, Ulrich and Oliva, Paulo B.",
title = 	 "Proof Mining: A Systematic Way of Analysing
Proofs in Mathematics",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-31",
month = 	 jun,
note = 	 "47~pp. Appears in {\em Proceedings of the
Steklov Institute of Mathematics},
242:136--164, 2003",
abstract = 	 "We call {\it proof mining} the process of
logically analyzing proofs in mathematics with
the aim of obtaining new information. In this
survey paper we discuss, by means of examples
from mathematics, some of the main techniques
used in proof mining. We show that those
techniques not only apply to proofs based on
classical logic, but also to proofs which
involve non-effective principles such as the
attainment of the infimum of $f\in C[0,1]$ and
the convergence for bounded monotone sequences
of reals. We also report on recent case studies
in approximation theory and fixed point theory
where new results were obtained",
}
@techreport{BRICS-RS-02-30,
author =	 "Danvy, Olivier and Schultz, Ulrik P.",
title =	 "Lambda-Lifting in Quadratic Time",
institution =	 brics,
year =	 2002,
type =	 rs,
number =	 "RS-02-30",
month =	 jun,
note =	 "17~pp. Appears in " # lncs2441 # ", pages
134--151. Superseeded by the BRICS report
abstract =	 "Lambda-lifting is a program transformation used in
compilers and in partial evaluators and that
operates in cubic time. In this article, we show how
to reduce this complexity to quadratic time.\bibpar
Lambda-lifting transforms a block-structured program
into a set of recursive equations, one for each
local function in the source program. Each equation
carries extra parameters to account for the free
variables of the corresponding local function and of
all its callees. It is the search for these extra
parameters that yields the cubic factor in the
traditional formulation of lambda-lifting, which is
due to Johnsson. This search is carried out by a
transitive closure.\bibpar Instead, we partition the
call graph of the source program into strongly
connected components, based on the simple
observation that all functions in each component
need the same extra parameters and thus a transitive
closure is not needed. We therefore simplify the
search for extra parameters by treating each
strongly connected component instead of each
function as a unit, thereby reducing the time
complexity of lambda-lifting from O(n3logn) to
O(n2logn), where n is the size of the program"
}
@techreport{BRICS-RS-02-29,
author = 	 "Pedersen, Christian N. S. and Scharling,
Tejs",
title = 	 "Comparative Methods for Gene Structure
Prediction in Homologous Sequences",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-29",
month = 	 jun,
note = 	 "20~pp. Appears in " # lncs2452 # ", pages
220--234",
abstract = 	 "The increasing number of sequenced genomes
motivates the use of evolutionary patterns to
detect genes. We present a series of
comparative methods for gene finding in
homologous prokaryotic or eukaryotic sequences.
Based on a model of legal genes and a
similarity measure between genes, we find the
pair of legal genes of maximum similarity. We
develop methods based on genes models and
alignment based similarity measures of
increasing complexity, which take into account
many details of real gene structures, e.g. the
similarity of the proteins encoded by the
exons. When using a similarity measure based on
an exiting alignment, the methods run in linear
time. When integrating the alignment and
prediction process which allows for more fine
grained similarity measures, the methods run in
quadratic time. We evaluate the methods in a
series of experiments on synthetic and real
sequence data, which show that all methods are
competitive but that taking the similarity of
the encoded proteins into account really boost
the performance",
}
@techreport{BRICS-RS-02-28,
author = 	 "Kohlenbach, Ulrich and Leu{\c{s}}tean,
Lauren{\c{t}}iu",
title = 	 "Mann Iterates of Directionally Nonexpansive
Mappings in Hyperbolic Spaces",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-28",
month = 	 jun,
note = 	 "33~pp. To appear in {\em Abstract and Applied
Analysis}.",
abstract = 	 "In a previous paper, the first author derived
an explicit quantitative version of a theorem
due to Borwein, Reich and Shafrir on the
asymptotic behaviour of Mann iterations of
nonexpansive mappings of convex sets $C$ in
normed linear spaces. This quantitative
version, which was obtained by a logical
analysis of the ineffective proof given by
Borwein, Reich and Shafrir, could be used to
obtain strong uniform bounds on the asymptotic
regularity of such iterations in the case of
bounded $C$ and even weaker conditions. In this
paper we extend these results to hyperbolic
spaces and directionally nonexpansive mappings.
In particular, we obtain significantly stronger
and more general forms of the main results of a
recent paper by W.A. Kirk with explicit bounds.
As a special feature of our approach, which is
based on logical analysis instead of functional
analysis, no functional analytic embeddings are
needed to obtain our uniformity results which
contain all previously known results of this
kind as special cases",
}
@techreport{BRICS-RS-02-27,
author = 	 "{\"O}stlin, Anna and Pagh, Rasmus",
title = 	 "Simulating Uniform Hashing in Constant Time
and Optimal Space",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-27",
month = 	 "",
note = 	 "11~pp",
abstract = 	 "Many algorithms and data structures employing
hashing have been analyzed under the {\em
uniform hashing} assumption, i.e., the
assumption that hash functions behave like
truly random functions. In this paper it is
shown how to implement hash functions that can
be evaluated on a RAM in constant time, and
behave like truly random functions on any set
of $n$ inputs, with high probability. The space
needed to represent a function is $O(n)$ words,
which is the best possible (and a polynomial
improvement compared to previous fast hash
functions). As a consequence, a broad class of
hashing schemes can be implemented to meet,
with high probability, the performance
guarantees of their uniform hashing analysis",
}

@techreport{BRICS-RS-02-26,
author = 	 "Korovina, Margarita",
title = 	 "Fixed Points on Abstract Structures without
the Equality Test",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-26",
month = 	 jun,
note = 	 "14~pp. Appears in " # lncs2850 # ", pages
290--301. Appeared earlier in " # ns022 # ",
pages 58--61",
abstract = 	 "In this paper we present a study of
definability properties of fixed points of
effective operators on abstract structures
without the~equality test. In particular we
prove that Gandy theorem holds for abstract
structures. This provides a useful tool for
dealing with recursive definitions using
$\Sigma$-formulas.\bibpar
One of the applications of Gandy theorem in the
case of the reals without the equality test is
that it allows us to define universal $\Sigma$--predicates. It leads to a topological
characterisation of $\Sigma$--relations on
${\rm I\!R}$",
}
@techreport{BRICS-RS-02-25,
author = 	 "H{\"u}ttel, Hans",
title = 	 "Deciding Framed Bisimilarity",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-25",
month = 	 may,
note = 	 "20~pp. Appears in " # entcsinfinity02 # ",
18~pp",
abstract = 	 "The spi-calculus, proposed by Abadi and
Gordon, is a process calculus based on the $\pi$-calculus and is intended for reasoning about
the behaviour of cryptographic protocols. We
consider the finite-control fragment of the
spi-calculus, showing it to be Turing-powerful
(a result which is joint work with Josva
Kleist, Uwe Nestmann, and Bj{\"o}rn Victor.)
Next, we restrict our attention to finite
(non-recursive) spi-calculus. Here, we show
that framed bisimilarity, an equivalence
relation proposed by Abadi and Gordon, showing
that it is decidable for this fragment",
}
@techreport{BRICS-RS-02-24,
author = 	 "Christensen, Aske Simon and M{\o}ller, Anders
and Schwartzbach, Michael I.",
title = 	 "Static Analysis for Dynamic {XML}",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-24",
month = 	 may ,
note = 	 "13~pp",
abstract = 	 "We describe the {\it summary graph} lattice
for dataflow analysis of programs that
dynamically construct XML documents. Summary
graphs have successfully been used to provide
static guarantees in the JWIG language for
programming interactive Web services. In
particular, the JWIG compiler is able to check
validity of dynamically generated XHTML
documents and to type check dynamic form data.
In this paper we present summary graphs and
indicate their applicability for various
scenarios. We also show that summary graphs
have exactly the same expressive power as the
regular expression types from XDuce, but that
the extra structure in summary graphs makes
them more suitable for certain program
analyses",
}

@techreport{BRICS-RS-02-23,
author = 	 "Nola, Antonio Di and Leu{\c{s}}tean, Lauren{\c
{t}}iu",
title = 	 "Compact Representations of {BL}-Algebras",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-23",
month = 	 may,
note = 	 "25~pp",
abstract = 	 "In this paper we define sheaf spaces of
BL-algebras (or BL-sheaf spaces), we study
completely regular and compact BL-sheaf spaces
and compact representations of BL-algebras and,
finally, we prove that the category of
non-trivial BL-algebras is equivalent with the
category of compact local BL-sheaf spaces",
}

@techreport{BRICS-RS-02-22,
author = 	 "Nielsen, Mogens and Palamidessi, Catuscia and
Valencia, Frank D.",
title = 	 "On the Expressive Power of Concurrent
Constraint Programming Languages",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-22",
month = 	 may,
note = 	 "34~pp. Appears in " # acmppdp02 # ", pages
156--157",
abstract = 	 "The tcc paradigm is a formalism for timed
concurrent constraint programming. Several tcc
languages differing in their way of expressing
infinite behaviour have been proposed in the
literature. In this paper we study the
expressive power of some of these languages. In
particular, we show that:
\begin{itemize}
\item[(1)] recursive procedures with parameters
can be encoded into parameterless recursive
procedures with dynamic scoping, and
vice-versa.
\item[(2)] replication can be encoded into
parameterless recursive procedures with
static scoping, and vice-versa.
\item[(3)]the languages from (1) are strictly
more expressive than the languages from (2).
\end{itemize}
Furthermore, we show that behavioural
equivalence is undecidable for the languages
from (1), but decidable for the languages from
(2). The undecidability result holds even if
the process variables take values from a fixed
finite domain",
}
@techreport{BRICS-RS-02-21,
author = 	 "{\'E}sik, Zolt{\'a}n and Kuich, Werner",
title = 	 "Formal Tree Series",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-21",
month = 	 apr,
note = 	 "66~pp",
abstract = 	 "In this survey we generalize some results on
formal tree languages, tree grammars and tree
automata by an algebraic treatment using
semirings, fixed point theory, formal tree
series and matrices. The use of these
mathematical constructs makes definitions,
constructions, and proofs more satisfactory
from an mathematical point of view than the
customary ones. The contents of this survey
paper is indicated by the titles of the
sections:
\begin{itemize}
\item[1.] Introduction
\item[2.] Preliminaries
\item[3.] Tree automata and systems of
equations
\item[4.] Closure properties and a Kleene
Theorem for recognizable tree series
\item[5.] Pushdown tree automata, algebraic
tree systems, and a Kleene Theorem
\item[6.] Tree series transducers
\item[7.] Full abstract families of tree series
\item[8.] Connections to formal power series
\end{itemize}
",
}

@techreport{BRICS-RS-02-20,
author = 	 "{\'E}sik, Zolt{\'a}n and Larsen, Kim G.",
title = 	 "Regular Languages Definable by {L}indstr{\"o}m
Quantifiers (Preliminary Version)",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-20",
month = 	 apr,
note = 	 "56~pp. Superseeded by the BRICS report
abstract = 	 "In our main result, we establish a formal
connection between Lindstr{\"o}m quantifiers
with respect to regular languages and the
double semidirect product of finite
monoid-generator pairs. We use this
correspondence to characterize the expressive
power of Lindstr{\"o}m quantifiers associated
with a class of regular languages",
}

@techreport{BRICS-RS-02-19,
author = 	 "Bloom, Stephen L. and {\'E}sik, Zolt{\'a}n",
title = 	 "An Extension Theorem with an Application to
Formal Tree Series",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-19",
month = 	 apr,
note = 	 "51~pp. Appears in " # entcsctcs02 # " under
the title {\em Unique Guarded Fixed Points in
abstract = 	 "A grove theory is a Lawvere algebraic theory
$T$ for which each hom-set $T(n,p)$ is a
commutative monoid; composition on the right
distrbutes over all finite sums: $(\sum_{i \in F} f_i) \cdot h= \sum_{i \in F} f_i \cdot h$. A
matrix theory is a grove theory in which
composition on the left and right distributes
over finite sums. A matrix theory $M$ is
isomorphic to a theory of all matrices over the
semiring $S=M(1,1)$. Examples of grove theories
are theories of (bisimulation equivalence
classes of) synchronization trees, and theories
of formal tree series over a semiring $S$. Our
main theorem states that if $T$ is a grove
theory which has a matrix subtheory $M$ which
is an iteration theory, then, under certain
conditions, the fixed point operation on $M$
can be extended in exactly one way to a
fixedpoint operation on $T$ such that $T$ is an
iteration theory. A second theorem is a
Kleene-type result. Assume that $T$ is a
iteration grove theory and $M$ is a sub
iteration grove theory of $T$ which is a matrix
theory. For a given collection $\Sigma$ of
scalar morphisms in $T$ we describe the
smallest sub iteration grove theory of $T$
containing all the morphisms in $M \cup\Sigma$",
}
@techreport{BRICS-RS-02-18,
author = 	 "Brodal, Gerth St{\o}lting and Fagerberg,
Rolf",
title = 	 "Cache Oblivious Distribution Sweeping",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-18",
month = 	 apr,
note = 	 "Appears in " # lncs2380 # ", pages 426--438",
abstract = 	 "We adapt the distribution sweeping method to
the cache oblivious model. Distribution
sweeping is the name used for a general
approach for divide-and-conquer algorithms
where the combination of solved subproblems can
be viewed as a merging process of streams. We
demonstrate by a series of algorithms for
specific problems the feasibility of the method
in a cache oblivious setting. The problems all
come from computational geometry, and are:
orthogonal line segment intersection reporting,
the all nearest neighbors problem, the 3D
maxima problem, computing the measure of a set
of axis-parallel rectangles, computing the
visibility of a set of line segments from a
point, batched orthogonal range queries, and
reporting pairwise intersections of
axis-parallel rectangles. Our basic building
block is a simplified version of the cache
oblivious sorting algorithm Funnelsort of Frigo
et al., which is of independent interest"
}

@techreport{BRICS-RS-02-17,
author = 	 "Madsen, Bolette Ammitzb{\o}ll and Byskov,
Jesper Makholm and Skjernaa, Bjarke",
title = 	 "On the Number of Maximal Bipartite Subgraphs
of a Graph",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-17",
month = 	 apr,
note = 	 "7~pp",
abstract = 	 "We show new lower and upper bounds on the
number of maximal induced bipartite subgraphs
of graphs with $n$ vertices. We present an
infinite family of graphs having $105^{n/10} \approx 1.5926^n$ such subgraphs, which
improves an earlier lower bound by Schiermeyer
(1996). We show an upper bound of $n\cdot 12^{n/4} \approx n\cdot 1.8613^n$ and give an
algorithm that lists all maximal induced
bipartite subgraphs in time proportional to
this bound. This is used in an algorithm for
checking 4-colourability of a graph running
within the same time bound",
}
@techreport{BRICS-RS-02-16,
author = 	 "Srba, Ji{\v{r}}{\'\i}",
title = 	 "Strong Bisimilarity of Simple Process
Algebras: Complexity Lower Bounds",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-16",
month = 	 apr,
note = 	 "33~pp. To appear in {\em Acta Informatica}",
abstract = 	 "In this paper we study bisimilarity problems
for simple process algebras. In particular, we
show PSPACE-hardness of the following problems:
\begin{enumerate}
\item strong bisimilarity of Basic Parallel
Processes (BPP),
\item strong bisimilarity of Basic Process
Algebra (BPA),
\item strong regularity of BPP, and
\item strong regularity of BPA.
\end{enumerate}
We also demonstrate NL-hardness of strong
regularity problems for the normed subclasses
of BPP and BPA.\bibpar
Bisimilarity problems for simple process
algebras are introduced in a general framework
of process rewrite systems, and a uniform
description of the new techniques used for the
hardness proofs is provided",
}
@techreport{BRICS-RS-02-15,
author = 	 "Nielsen, Jesper Makholm",
title = 	 "On the Number of Maximal Independent Sets in a
Graph",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-15",
month = 	 apr,
note = 	 "10~pp",
abstract = 	 "We show that the number of maximal independent
sets of size {\em exactly} $k$ in any graph of
size $n$ is at most $\lfloor n/k \rfloor ^{k-(n\bmod k)} (\lfloor n/k \rfloor+1)^{n\bmod k}$. For maximal independent sets of size {\em
at most} $k$ the same bound holds for $k\leq n/3$. For $k>n/3$ a bound of approximately
$3^{n/3}$ is given. All the bounds are exactly
tight and improve Eppstein (2001) who give the
bound $3^{4k-n}4^{n-3k}$ on the number of
maximal independent sets of size at most $k$,
which is the same for $n/4 \leq k \leq n/3$,
but larger otherwise. We give an algorithm
listing the maximal independent sets in a graph
in time proportional to these bounds (ignoring
a polynomial factor), and we use this algorithm
to construct algorithms for 4- and 5- colouring
running in time ${\cal O}(1.7504^n)$ and ${\cal O}(2.1593^n)$, respectively",
}

@techreport{BRICS-RS-02-14,
author = 	 "Berger, Ulrich and Oliva, Paulo B.",
title = 	 "Modified Bar Recursion",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-14",
month = 	 apr,
note = 	 "23~pp. To appear in {\em Lecture Notes in
Logic}",
abstract = 	 "We introduce a variant of Spector's bar
recursion (called modified bar recursion'')
in finite types to give a realizability
interpretation of the classical axiom of
countable choice allowing for the extraction of
witnesses from proofs of $\Sigma_1$ formulas in
classical analysis. As a second application of
modified bar recursion we present a bar
recursive definition of the fan functional.
Moreover, we show that modified bar recursion
exists in ${\cal M}$ (the model of strongly
majorizable functionals) and is not S1-S9
computable in ${\cal C}$ (the model of total
functionals). Finally, we show that modified
bar recursion defines Spector's bar recursion
primitive recursively",
}
@techreport{BRICS-RS-02-13,
author = 	 "Brodal, Gerth St{\o}lting and Lyngs{\o}, Rune
B. and {\"O}stlin, Anna and Pedersen, Christian
N. S.",
title = 	 "Solving the String Statistics Problem in Time
$O(n\log n)$",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-13",
month = 	 mar,
note = 	 "28~pp. Shorter version appears in " # lncs2380
# ", pages 728--739",
abstract = 	 "The string statistics problem consists of
preprocessing a string of length~$n$ such that
given a query pattern of length~$m$, the
maximum number of non-overlapping occurrences
of the query pattern in the string can be
reported efficiently. Apostolico and Preparata
introduced the minimal augmented suffix tree
(MAST) as a data structure for the string
statistics problem, and showed how to construct
the MAST in time ${\cal O}(n\log^2 n)$ and how
it supports queries in time~${\cal O}(m)$ for
constant sized alphabets. A subsequent theorem
by Fraenkel and Simpson stating that a string
has at most a linear number of distinct squares
implies that the MAST requires space~${\cal O}(n)$. In this paper we improve the
construction time for the MAST to ${\cal O}(n\log n)$ by extending the algorithm of
Apostolico and Preparata to exploit properties
of efficient joining and splitting of search
trees together with a refined analysis",
}

@techreport{BRICS-RS-02-12,
author = 	 "Danvy, Olivier and Goldberg, Mayer",
title = 	 "There and Back Again",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-12",
month = 	 mar,
note = 	 "ii+11~pp. Appears in " # acmicfp02 # ", pages
230--234. This report supersedes the earlier
report BRICS RS-01-39",
abstract = 	 "We present a programming pattern where a
recursive function traverses a data
structure---typically a list---at return time.
The idea is that the recursive calls get us
there (typically to a base case) and the
returns get us back again {\em while traversing
the data structure}. We name this programming
pattern of traversing a data structure at
return time There And Back Again''
(TABA).\bibpar
The TABA pattern directly applies to computing
a symbolic convolution. It also synergizes well
with other programming patterns, e.g., dynamic
programming and traversing a list at double
speed. We illustrate TABA and dynamic
programming with Catalan numbers. We illustrate
TABA and traversing a list at double speed with
palindromes and we obtain a novel solution to
A TABA-based function written in direct style
makes full use of an Algol-like control stack
and needs no heap allocation. Conversely, in a
TABA-based function written in
continuation-passing style, the continuation
acts as a list iterator. In general, the TABA
pattern saves one from constructing
intermediate lists in reverse order",
}

@techreport{BRICS-RS-02-11,
author = 	 "Christensen, Aske Simon and M{\o}ller, Anders
and Schwartzbach, Michael I.",
title = 	 "Extending Java for High-Level Web Service
Construction",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-11",
month = 	 mar,
note = 	 "54~pp. To appear in {\em ACM Transactions on
Programming Languages and Systems}",
abstract = 	 "We incorporate innovations from the {\tt
} project into the Java language to
provide high-level features for Web service
programming. The resulting language, JWIG,
contains an advanced session model and a
flexible mechanism for dynamic construction of
XML documents, in particular XHTML. To support
program development we provide a suite of
program analyses that at compile-time verify
for a given program that no run-time errors can
occur while building documents or receiving
form input, and that all documents being shown
are valid according to the document type
definition for XHTML 1.0.\bibpar
We compare JWIG with Servlets and JSP which are
widely used Web service development platforms.
Our implementation and evaluation of JWIG
indicate that the language extensions can
simplify the program structure and that the
analyses are sufficiently fast and precise to
be practically useful",
}
@techreport{BRICS-RS-02-10,
author = 	 "Kohlenbach, Ulrich",
title = 	 "Uniform Asymptotic Regularity for {M}ann
Iterates",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-10",
month = 	 mar,
note = 	 "17~pp. Appears in {\em Journal of Mathematical
Analysis and Applications}, 279(2):531--544,
2003.",
abstract = 	 "In a previous paper we obtained an effective
quantitative analysis of a theorem due to
Borwein, Reich and Shafrir on the asymptotic
behavior of general Krasnoselski-Mann
iterations for nonexpansive self-mappings of
convex sets $C$ in arbitrary normed spaces. We
used this result to obtain a new strong uniform
version of Ishikawa's theorem for bounded $C$.
In this paper we give a qualitative improvement
of our result in the unbounded case and prove
the uniformity result for the bounded case
under the weaker assumption that $C$ contains a
point $x$ whose Krasnoselski-Mann iteration
$(x_n)$ is bounded.\\
We also consider more general iterations for
which asymptotic regularity is known only for
uniformly convex spaces (Groetsch). We give
uniform effective bounds for (an extension of)
Groetsch's theorem which generalize previous
results by Kirk/Martinez-Yanez and the author",
}
@techreport{BRICS-RS-02-9,
author = 	 "{\"O}stlin, Anna and Pagh, Rasmus",
title = 	 "One-Probe Search",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-9",
month = 	 feb,
note = 	 "17~pp. Appears in " # lncs2380 # ", pages
439--450",
abstract = 	 "We consider dictionaries that perform lookups
by probing a {\em single word\/} of memory,
knowing only the size of the data structure. We
describe a randomized dictionary where a lookup
returns the correct answer with probability
$1-\epsilon$, and otherwise returns don't
know''. The lookup procedure uses an expander
graph to select the memory location to probe.
Recent explicit expander constructions are
shown to yield space usage much smaller than
what would be required using a deterministic
lookup procedure. Our data structure supports
efficient {\em deterministic\/} updates,
exhibiting new probabilistic guarantees on
dictionary running time",
}

@techreport{BRICS-RS-02-8,
author = 	 "Cramer, Ronald and Fehr, Serge",
title = 	 "Optimal Black-Box Secret Sharing over
Arbitrary Abelian Groups",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-8",
month = 	 feb,
note = 	 "19~pp. Appears in " # lncs2442 # ", pages
272--287",
}
@techreport{BRICS-RS-02-7,
author = 	 "Ing{\'o}lfsd{\'o}ttir, Anna and Christensen,
Anders Lyhne and Hansen, Jens Alsted and
Johnsen, Jacob and Knudsen, John and Rasmussen,
Jacob Illum",
title = 	 "A Formalization of Linkage Analysis",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-7",
month = 	 feb,
note = 	 "vi+109~pp",
abstract = 	 "In this report a formalization of genetic
analysis is a computationally hard
biomathematical method, which purpose is to
locate genes on the human genome. It is rooted
in the new area of bioinformatics and no
formalization of the method has previously been
established. Initially, the biological model is
presented. On the basis of this biological
model we establish a formalization that enables
analysis. The formalization applies both for
single and multi point linkage analysis. We
illustrate the usage of the formalization in
correctness proofs of central algorithms and
optimisations for linkage analysis. A further
use of the formalization is to reason about
alternative methods for linkage analysis. We
discuss the use of MTBDDs and PDGs in linkage
analysis, since they have proven efficient for
other computationally hard problems involving
large state spaces. We conclude that none of
the techniques discussed are directly
applicable to linkage analysis, however further
research is needed in order to investigated
whether a modified version of one or more of
these are applicable",
}

@techreport{BRICS-RS-02-6,
author = 	 "Aceto, Luca and {\'E}sik, Zolt{\'a}n and
Ing{\'o}lfsd{\'o}ttir, Anna",
title = 	 "Equational Axioms for Probabilistic
Bisimilarity (Preliminary Report)",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-6",
month = 	 feb,
note = 	 "22~pp. Appears in " # lncs2422 # ", pages
239--253",
abstract = 	 "This paper gives an equational axiomatization
of probabilistic bisimulation equivalence for a
class of finite-state agents previously studied
by Stark and Smolka ((2000) {\em Proof,
Language, and Interaction: Essays in Honour of
Robin Milner}, pp.~571--595). The
axiomatization is obtained by extending the
general axioms of iteration theories (or
iteration algebras), which characterize the
equational properties of the fixed point
operator on ($\omega$-)\-continuous or
monotonic functions, with three axiom schemas
that express laws that are specific to
probabilistic bisimilarity. Hence probabilistic
bisimilarity (over finite-state agents) has an
equational axiomatization relative to iteration
algebras",
}

@techreport{BRICS-RS-02-5,
author = 	 "Crazzolara, Federico and Winskel, Glynn",
title = 	 "Composing {S}trand Spaces",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-5",
month = 	 feb,
note = 	 "30~pp",
abstract = 	 "The strand space model for the analysis of
security protocols is known to have some
limitations in the patterns of nondeterminism
it allows and in the ways in which strand
spaces can be composed. Its successful
application to a broad range of security
protocols may therefore seem surprising. This
paper gives a formal explanation of the wide
applicability of strand spaces. We start with
an extension of strand spaces which permits
several operations to be defined in a
compositional way, forming a process language
for building up strand spaces. We then show,
under reasonable conditions how to reduce the
extended strand spaces to ones of a traditional
kind. For security protocols we are mainly
interested in their safety properties. This
suggests a strand-space equivalence: two strand
spaces are equivalent if and only if they have
essentially the same sets of bundles. However
this equivalence is not a congruence with
respect to the strand-space operations. By
extending the notion of bundle we show how to
define the strand-space operations directly on
bundle spaces''. This leads to a
characterisation of the largest congruence
within the strand-space equivalence. Finally,
we relate strand spaces to event structures, a
well known model for concurrency.",
}

@techreport{BRICS-RS-02-4,
author = 	 "Danvy, Olivier and Nielsen, Lasse R.",
title = 	 "Syntactic Theories in Practice",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-4",
month = 	 jan,
note = 	 "34~pp. This revised report supersedes the
earlier BRICS report RS-01-31",
abstract = 	 "The evaluation function of a syntactic theory
is canonically defined as the transitive
closure of (1) decomposing a program into an
evaluation context and a redex, (2) contracting
this redex, and (3) plugging the contractum in
the context. Directly implementing this
evaluation function therefore yields an
interpreter with a worst-case overhead, for
each step, that is linear in the size of the
input program. We present sufficient conditions
over a syntactic theory to circumvent this
overhead, by replacing the composition of (3)
plugging and (1) decomposing by a single
refocusing'' function mapping a contractum
and a context into a new context and a new
redex, if there are any. We also show how to
construct such a refocusing function, we prove
its correctness, and we analyze its
complexity.\bibpar
We illustrate refocusing with two examples: a
programming-language interpreter and a
transformation into continuation-passing style.
As a byproduct, the time complexity of this
program transformation is mechanically changed
from quadratic in the worst case to linear",
}

@techreport{BRICS-RS-02-3,
author = 	 "Danvy, Olivier and Nielsen, Lasse R.",
title = 	 "On One-Pass {CPS} Transformations",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-3",
month = 	 jan,
note = 	 "18~pp",
abstract = 	 "We bridge two distinct approaches to one-pass
CPS transformations, i.e., CPS transformations
that reduce administrative redexes at
transformation time instead of in a
post-processing phase. One approach is
compositional and higher-order, and is due to
Appel, Danvy and Filinski, and Wand, building
on Plotkin's seminal work. The other is
non-compositional and based on a syntactic
theory of the $\lambda$-calculus, and is due to
Sabry and Felleisen. To relate the two
approaches, we use Church encoding, Reynolds's
defunctionalization, and an implementation
technique for syntactic theories, refocusing,
developed in the second author's PhD
thesis.\bibpar
This work is directly applicable to
transforming programs into monadic normal
form",
}

@techreport{BRICS-RS-02-2,
author = 	 "Nielsen, Lasse R.",
title = 	 "A Simple Correctness Proof of the Direct-Style
Transformation",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-2",
month = 	 jan,
note = 	 "11~pp",
abstract = 	 "We build on Danvy and Nielsen's first-order
program transformation into
continuation-passing style (CPS) to present a
new correctness proof of the converse
transformation, i.e., a one-pass transformation
from CPS back to direct style. Previously
published proofs were based on, e.g., a
one-pass higher-order CPS transformation, and
were complicated by having to reason about
higher-order functions. In contrast, this work
is based on a one-pass CPS transformation that
is both compositional and first-order, and
therefore the proof simply proceeds by
structural induction on syntax",
}

@techreport{BRICS-RS-02-1,
author = 	 "Brabrand, Claus and M{\o}ller, Anders and
Schwartzbach, Michael I.",
title = 	 "The {\tt} Project",
institution =  brics,
year = 	 2002,
type = 	 rs,
number = 	 "RS-02-1",
month = 	 jan,
note = 	 "36~pp. This revised report supersedes the
earlier BRICS report RS-00-42",
abstract = 	 "We present the results of the {\tt}
project, which aims to design and implement a
high-level domain-specific language for
programming interactive Web services.\bibpar
A fundamental aspect of the development of the
World Wide Web during the last decade is the
gradual change from static to dynamic
generation of Web pages. Generating Web pages
dynamically in dialogue with the client has the
advantage of providing up-to-date and
tailor-made information. The development of
systems for constructing such dynamic Web
services has emerged as a whole new research
area.\bibpar
The {\tt} language is designed by
analyzing its application domain and
identifying fundamental aspects of Web services
inspired by problems and solutions in existing
Web service development languages. The core of
the design consists of a session-centered
service model together with a flexible
template-based mechanism for dynamic Web page
construction. Using specialized program
analyses, certain Web specific properties are
verified at compile-time, for instance that
only valid HTML 4.01 is ever shown to the
clients. In addition, the design provides
high-level solutions to form field validation,
caching of dynamic pages, and temporal-logic
based concurrency control, and it proposes
syntax macros for making highly domain-specific
languages. The language is implemented via
widely available Web technologies, such as
Apache on the server-side and JavaScript and
Java Applets on the client-side. We conclude
with experience and evaluation of the project",
`