Table Of ContentLecture Notes in Computer Science 1139
Edited by G. Goos, J. Hartmanis and J. van Leeuwen
Advisory Board: W. Brauer D. Gries J. Stoer
Michael Hanus
Mario Rodrfguez-Artalejo (Eds.)
ciarbeglA dna cigoL
gnimmargorP
5th International Conference, ALP'96
Aachen, Germany, September 25-27, 1996
Proceedings
regnirpS
Series Editors
Gerhard Goos, Karlsruhe University, Germany
Juris Hartmanis, Corneil University, ,YN USA
Jan van Leeuwen, Utrecht University, The Netherlands
Volume Editors
Michael Hanus
RWTH Aachen, Lehr- und Forschungsgebiet Informatik II
AhornstraBe 55, D-52074Aachen, Germany
E-mail: hanus @ informatik.rwth-aachen.de
Mario Rodrfguez-Artalejo
Universidad Complutense, Dto. de Informatica yAutomatica
Av. Complutense s/n, 28040 Madrid, Spain
E-mail: [email protected]
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Die Deutsche Bibliothek - CIP-Einheitsaufnahme
Algebraic dna logic programming (cid:12)9 5th international conference
; proceedings / ALP '96, Aachen, Germany, September 25 - 27,
1996. Michael Hanus ; Mario Rodriguez Artalejo (ed.). - Berlin
; Heidelberg ; New York ; Barcelona ; Budapest ; Hong Kong ;
London ; Milan ; Paris ; Santa Clara ; Singapore ; Tokyo :
Springer, 1996
(Lecture notes in computer science ; Vol. )9311
ISBN 3-540-61735-3
NE: Hanus, Michael Hrsg.; ALP <5, 1996, Aachen>; GT
CR Subject Classification (1991): D.3,F.3-4, 1.2.3
ISSN 0302-9743
ISBN 3-540-61735-3 Springer-Verlag Berlin Heidelberg New York
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(cid:14)9 Springer-Verlag Berlin Heidelberg 1996
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Preface
This volume contains the proceedings of the Fifth International Conference on
Algebraic and Logic Programming (ALP'96), held in Aachen (Germany) during
September 25-27, 1996. The conference was preceded by previous meetings in
Gaussig (1988), Nancy (1990), Volterra (1992), and Madrid (1994). The previous
proceedings have been published by Springer-Verlag, as in this case, as Lecture
Notes in Computer Science, volumes 343,463,632, and 850, respectively.
Following the intention of the previous ALP meetings, the conference aims at
strengthening the connections between algebraic techniques and logic program-
ming. On the one hand, logic programming has been very successful during the
last two decades, and many efforts have been made to enhance its expressive
power and efficiency, including in particular the emergence of constraint logic
programming. On the other hand, concepts such as functions, types, equational
theories, and modularity are particularly well handled in an algebraic frame-
work. As during the previous conferences, ALP promotes the cross-fertilizing
exchange of ideas and experiences among researchers from the algebraic and
logic programming communities.
On this occasion, ALP was held concurrently with the Eighth Interna-
tional Symposium on Programming Languages, Implementations, Logics, and
Programs (PLILP'96) and the Third International Static Analysis Symposium
(SAS'96).
The ALP'96 Program Committee met in Aachen on June 22, 1996. Shortly
before this meeting, there was an email discussion of those papers for which there
was a significant disagreement about the technical quality. Finally, the Program
Committee selected 12 papers from 54 submissions. In addition to the selected
papers, the scientific program included invited lectures (shared with PLILP'96
and SAS'96) by Claude Kirchner, Lambert Meertens, and Bernhard Steffen. The
invited paper by Ilies Alouini and Claude Kirchner is included in this volume.
We would like to thank all the members of the Program Committee and all
the referees for their careful work in the reviewing and selection process.
The organization of the conferences was supported by
- The Assocation of Logic Programming
Esprit Compulog-Net
-
RWTH Aachen
- - SUN Microsystems
Finally, we express our gratitude to all members of the local Organizing Com-
mittee for their help in organizing a successful event.
Aachen Michael Hanus
Madrid Mario Rodrfguez-Artalejo
July 1996 Program Committee Chairmen
Iv
Program Committee Chairmen
Michael Hanus (Germany)
Mario Rodrlguez-Artalejo (Spain)
Program Committee
Sergio Antoy (USA) Luis Monteiro (Portugal)
Egidio Astesiano (Italy) Fernando Orejas (Spain)
Jiirgen Avenhaus (Germany) Catuscia Palamidessi (Italy)
Pierre Deransart (France) Frank Pfenning (USA)
Laurent Fribourg (France) Vijay Saraswat (USA)
Joxan Jaffar (Singapore) Peter Stuckey (Australia)
Giorgio Levi (Italy) Andrzej Tarlecki (Poland)
Karl Meinke (UK) Andrei Voronkov (Sweden)
Aart Middeldorp (Japan) Martin Wirsing (Germany)
Local Organization
Michael Hanus, Herbert Kuchen, Markus Mohnen, Ulla Oebel, Frank Zartmann,
Olaf Chitil, Arnd Gehrmann
List of Referees
J. Alferes, .Z Ariola, P. Barahona, M. Bednarczyk, .M Bidoit, S. Blom, N.
Boland, A. Borzyszkowski, .L Caires, .M Carlsson, M. Cerioli, P. Chambre,
W.N. Chin, O. Chitil, M. Comini, H. Comon, M.-M. Corsini, J.N. Crossley,
A. Degtyarev, G. Delzanno, J. Denzinger, W. Drabent, A. Ed-Dbali, S. Etalle,
M. Falaschi, C. Fecht, C. Fermiiller, M. Fernandez, J.A. Ferngndez, R. Fet-
tig, T. Fruehwirth, M. Gabbrielli, .M Garcia de la Banda, M. Gaspari, A.
Gavilanes-Franeo, A. Geser, R. Giacobazzi, J.C. Gonzs B. Gram-
lich, M. Hamana, W. Harvey, T. Hortals ~A Hui-Bon-Hoa, S. Kahrs,
S. Kekkonen, R. Kennaway, S.C. Khoo, C. Kirchner, J.W. Klop, T. Knapik,
P. Kosiuezenko, F. Laburthe, A. Lallouet, T. Lindgren, F. L6pez-Fraguas, B.
Malfon, P. Mancarella, N. Martf-Oliet, P.-A. Melli~s, P. Mello, M.-C. Meo, D.
Miller, H. Millroth, E. Moggi, M. Mohnen, L. Monteiro, T. Mora, A. Mycroft, G.
Nadathur, C.W. Ngan, R. Nieuwenhuis, S. Nieva-Soto, E. Ohlebusch, H. ,n@slO
V. van Oostrom, P. P~czkowski, E. Palmgren, W. Pawtowski, .L M. Pereira,
E. Pimentel-Ss A. Porto, F. van Raamsdonk, G. Reggio, .S Renault, B.
Reus, J.-H. Rety, J. Richardson, .S Ronchi della Rocea, A. Rubio, S. Ruggieri,
M. Rusinowitch, F. Ss A. Sattler-Klein, .M Schmidt-Schaufl, D. Seipel,
R. Sekar, H. Scndergaard, M. Thielscher, A. Tolmach, R. Treinen, M. Veanes, P.
Volpe, F.-J. de Vries, M. Wallace, T. Yamada, R. Yap, H. Zantema, F. Zartmann
Table of Contents
Invited Talk
Toward the Concurrent Implementation of Computational Systems .......... i
Ilies Alouini and Claude Kirchner
Logic Programming
On Negation as Instantiation .............................................. 32
Alessandra Di Pierro and Wtodzimierz Drabent
Independence in Dynamically Scheduled Logic Languages .................. 47
Maria Garcia de la Banda, Manuel Hermenegildo, and Kim Marriott
Heterogeneous Constraint Solving ......................................... 62
Frdddric Benhamou
A Hierarchy of Semantics for Normal Constraint Logic Programs ........... 77
Franfois Fages and Roberta Gori
Term Rewriting
Order-Sorted Termination: The Unsorted Way ............................. 92
Peter Csaba ~)Iveczky and Olav Lysne
Unravelings and Ultra-properties ......................................... 107
Massimo Marchiori
Standardization Theorem Revisited ...................................... 122
Taro Suzuki
Discrete Normalization and Standardization in Deterministic Residual
Structures ............................................................... 135
Zurab Khasidashvili and John Glauert
Integration of Paradigms
A Language for the Logical Specification of Processes and Relations ...... 150
Lugs Caires
A Process Algebra for Synchronous Concurrent Constraint Programming . 165
Lubo~ Brim, David Gilbert, Jean-Marie Jaequet, and Mojmir K~etinsk~j
An Algebraic Approach to Mixins and Modularity ........................ 179
Davide Ancona and Elena Zucca
A Strict Border for the Decidability of E-Unification for Recursive Functions 194
Heinz Faflbender and Sebastian Maneth
ltly
Abstract Interpretation
Prime Factorizations of Abstract Domains Using First Order Logic ....... 209
Elena Marchiori
Abstractions of Uniform Proofs ........................................... 224
Paolo Volpe
Complementing Logic Program Semantics ................................ 238
Roberto Giacobazzi and Francesco Ranzato
Lambda-Calculus and Rewriting
Meaningless Terms in Rewriting .......................................... 254
Richard Kennaway, Vincent van Oostrom, and Fer-Jan de Vries
Unique Normal Form Property of Higher-Order Rewriting Systems ....... 269
Ken Mano and Mizuhito Ogawa
)~-Calculi with Explicit Substitutions and Composition which Preserve
/?-strong Normalization (Extended Abstract) ............................. 284
Maria C.F. Ferreira, Delia Kesner, and Laurence Puel
Types
Algebraic Semantics for Functional Logic Programming with
Polymorphic Order-Sorted Types ......................................... 299
Jesds M. Almendros-Jimdnez, Antonio. Gavilanes-Franco, and Ana Gil-Luezas
Specifying Type Systems ................................................. 314
Dieter Nazareth
The Semantic Treatment of Polymorphic Specification Languages ......... 330
Dieter Nazareth
Author Index .......................................................... 345
Toward the Concurrent Implementation of
Computational Systems
Ilies Alouini and Claude Kirchner
INRIA-LorrMne & CRIN
http://www.loria.fr/equipe/protheo.html
BP 101, 54602 Villers-l~s-Nancy FRANCE
E-m~l: {Ilies.Alouini, Claude.Kirchner)@Ioria.fr
Abstract. This paper places concurrent rewriting in the perspective
of supporting the development and use of computational systems. We
briefly recall the usefulness of computational systems (i.e. a rewriting
theory with strategies) as a logical framework. We then show that the
right implementation model for concurrent rewriting allows us to give
a meaning to the concurrent rewrite of overlapping redexes. The princi-
ples of the implementation of concurrent rewriting and of the associated
garbage collection are sketched. We then present a specific transforma-
tion of conditional rewriting to unconditional rewriting, that permits us
to preserve the potential concurrency of the system as much as possible.
This allows us to extend the ReCo system to handle conditional specifi-
cations. We finally present experimental results of the system on various
parallel architectures.
1 Introduction
The fundamental interest of using term rewriting as an executable specification
tool was shown in the last two decades, through many theoretical works but also
many implementations of the concept, like (without exhaustivity) OBJ, PLUSS,
LPG, .FDS-~-FSA More recently the usefulness of the rewriting logic as a logical
framework MOM93 and the resulting implementation of the ELAN KKV95
and MAUDE Mes93 languages have shown the importance of having efficient
implementations of conditional term rewriting with strategies, in particular in
parallel.
Initiated in the mid eighties for improving the efficiency of term normal-
isation, the idea of using concurrent term rewriting as a model of computa-
tion GKM87 has drawn lots of attention, either when designing specific hard-
ware for implementing the concepts GKL+86, or for the theoretical interest
of conditional rewriting as a model of fine grain concurrency Mes92, Vir94,
DL95, Mes96, or when implementing rewriting on distributed memory ma-
chines KV92, Vir92. This last work leads to the development in our research
group of ReCo, an implementation of concurrent rewriting on distributed mem-
ory machines. This system is presented later in the paper from the theoretical
background to the implementation model of the unconditional and conditional
cases. In particular, we show how conditional concurrent term rewriting can be
implemented on distributed memory machines (or a network of machines) by
providing a specially designed reduction of conditional concurrent rewriting to
unconditional concurrent rewriting.
Implementing concurrent rewriting is not an easy task since one has to first
design the right implementation model and then to design and implement the
right environment, including in particular garbage collection. In our case we
have shown that it is correct and complete to use the notion of jungle HP88
in order to provide the basis for the implementation KV92 and that in this
context a concurrent garbage collector can be designed and implemented Alo95.
In this paper, we furthermore show that our computation model is compatible
with the concurrent evaluation of overlapping redexes. This allows us to have
a truly asynchronous implementation of concurrent rewriting where forests of
terms are rewritten but a distinguished element of this forest represents the
term of interest.
This paper places concurrent rewriting in the perspective of supporting the
development and use of computational systems. So we begin in the next section
with a summary of the use of computational systems, especially in the context of
Algebraic and Logic Programming. Then we present the theoretical background
of computational systems and concurrent rewriting. We show how rewriting can
be implemented using a fine grained model on distributed memory machines
and we shortly recall how garbage collection works in this context. Then we
reduce conditional concurrent rewriting to unconditional conditional rewriting~
using a transformation specifically designed to preserve concurrency as much
as possible. Finally in the conclusion we outline the questions raised by this
approach, in particular when using strategies.
2 Computational systems
Computational systems have been introduced in the early nineties, for describing
inference systems as rewrite rules. Computational systems KKV95 are rewrite
theories in rewriting logic Mes92, together with strategies. We will see in the
next section how this can be formally defined. Let us first outline how conve-
nient computational systems can be for expressing inference systems of com-
mon use in the algebraic and logic programming community. In fact, the rule-
based approach of general deduction presented in MOM93, as well as specific
ones as advocated for unification IJK91, disunification Comgl, constraint solv-
ing CDJK95 or theorem proving~ can be realistically used in order to directly
implement these concepts. This is made concrete using ELAN BKK+96b, our
implementation of computational systems, which is used for running all the ex-
amples presented now.
ELAN, considered as a logical framework, makes rewriting logic available to
the user for representing its own logic. A standard library is provided with the
language to avoid the need for the the user to write again 1M the basic objects
like terms, integers or substitutions and their application. Starting from this,
one may first want, for example, to describe the standard unification algorithm.
Following JK91, and assuming the symbol f to be generic in the given signa-
ture~ the decomposition rule is expressed as usual by:
Decompose P A f(sl,...,s,~)=? f(tl,...,t,,) ~ P A sl ?= tl A ... A s~=? t.
which is written in ELAN as:
rule decompose
declare s_l, .... s_N:term; t_i .... ,t_N:term;
body
P & F(s_1 ..... s_N)=F(t 1,...,t_N) => P { & s_I=t_I }_I=I...N
end
In addition to offering a syntax very close to the one in use when describing
inference systems, ELAN allows us to describe strategies that are used to apply
the rules to a query. In the case of this example a possible unification strategy
is:
strategy unify
repeat
dont care choose(delete decompose conflict coalesce occCheck eliminate)
endrepeat
dont care choose(trueelim truepropag falsepropag)
end of strategy
which means that the rules delete, decompose, conflict, ... are applied until
none is applicable.
Building on this, a simple programming language based on Horn clause logic
and SLD-resolution can be described by a computational system: In Horn clause
logic, formulas are of the form A ~ B1,..., Bn with A, Bi being atoms, and a
theory is given by a signature and a set of formulas. SLD-resolution is mainly de-
scribed with two rules that are direct translations of the resolution and reflection
rules. This is fully described in Vit94, KKV95.
In the same vein, the narrowing relations, and in particular the Basic ver-
sion, are especially useful in the integration of functional and logic program-
ming Han94. The computational system describing Basic narrowing is given by
the two main rewrite rules:
Narrow (3X, g = d S) ~ (3X U 1;ar(l, r), gr~ = d I S A (glw =~ ))1
if l +-- r 6 Variants(PgR) and
(S A wlg( ~---- l)) is satisfiable
Block (3X, g = d II S) ~4~, (3X, T ISA (g =~ d))
if (S A (g =~ d)) is satisfiable
where on the left side of the II symbol appears the constraint to be solved
modulo the term rewriting system PgR (i.e. the rewrite program). On the right
side of this symbol appears the constraint to be solved in the empty theory (i.e.
