Subject: FORTE'95 Final Program

From: [email-masked] (Daniel Ouimet)
Date: Thu, 14 Sep 1995 16:47:49 -0400

FINAL PROGRAM

8th International Conference on FORMAL DESCRIPTION TECHNIQUES
for Distributed Systems and Communications Protocols (FORTE'95)
October 17 - 20, 1995 Montreal, Quebec, Canada

Sponsored by IFIP WG 6.1

Organized by:
Conference co-chairs
           Gregor v. Bochmann, Universite de Montreal and CRIM
           Rachida Dssouli, Universite de Montreal
           Omar Rafiq, Universite de Pau, France
Local Arrangements, Registrations and Treasury
           Lucie Levesque, Universite de Montreal
Coordination of tool demonstrations
           Daniel Ouimet, Universite de Montreal

Program Committee:
P. Amer (U. Delaware, USA), T. Bolognesi (CNUCE, Italy)
J. Bowen (U. Oxford, UK), E. Brinksma (U. Twente, Netherlands)
A. Cavalli (INT, France), S.T. Chanson (U. British Columbia, Canada)
J.P. Courtiat (LAAS, France), P. Dembinski (Academy of Science, Poland)
J. de Meer (GMD FOKUS, Germany), M. Ferguson (INRS, Canada)
R. Gotzhein (U. Kaiserslautern, Germany), M. Gouda (U. Texas, Austin, USA)
R. Groz (CNET, France), D. Hogrefe (U. Bern, Switzerland)
Y. Hirakawa (NTT, Japan), G. Holzmann (AT&T, USA), T. Kato (KDD, Japan)
L. Kovacs (CAI, Hungaria), J. Kroon (PTT Research, Netherlands)
G. Leduc (U. Liege, Belgium), L. Logrippo (U. Ottawa, Canada)
G. Luo (BNR, Canada), L. Marshall (BNR, Canada), E. Najm (ENST, France)
A. Obaid (UQAH, Canada), K. Parker (Telecom Research Lab., Australia)
A. Petrenko (U. Montreal, Canada), J. Quemada (Technical U. Madrid, Spain)
S.V. Raghavan (IIT, Madras, India), H. Rudin (IBM, Switzerland)
K. Saleh (Kuwait U., Kuwait), B. Sarikaya (U. Aizu, Japan)
R. Tenney (U. Massachusetts, USA), K. Turner (U. Stirling, UK)
S.T. Vuong (U. British Columbia, Canada)

Financial Support from:
INRS-Telecommunications
Universite de Montreal
Computer Research Institute of Montreal, (CRIM)
Hewlett Packard-NSERC-CITI Industrial Research Chair on Communication Protocols
Bell Canada

TUTORIALS

TUESDAY, October 17

Registration:  07h30 - 09h00

Room 1 - Location:  Salon Le Castillon

Tutorial: (with midmorning coffee) 09h00 - 12h00
Symbolic Model Checking
  Edmund M. Clarke (School of Computer Science Carnegie Mellon University, USA)

     Logical errors in finite state reactive systems are an important problem 
for designers. They can delay getting a new product on the market or cause the 
failure of some critical device that is already in use.  My research group has 
developed a verification method called {temporal logic model checking} for
this class of systems.  In this approach specifications are expressed in a
propositional temporal logic, and reactive systems are modeled as
state-transition graphs.  An efficient search procedure is used to determine
automatically if the specifications are satisfied by the state-transition
graph.  The technique has been used in the past to find subtle errors in a
number of non-trivial circuit and protocol designs.  During the last few
years, the size of the reactive systems that can be verified by model
checking techniques has increased dramatically.  By representing sets of
states and transition relations implicitly using Binary Decision Diagrams
(BDDs), we are now able to check examples that are many orders of magnitude
larger than was previously the case.  In this tutorial we describe how the
BDD-based model checking techniques work and illustrate their power by
discussing the verification of several complex protocol and circuit designs.

Lunch at the Hotel:   12:00 - 13:30  -  Salle a diner Le Castillon

Tutorial:  13h30 - 16h30
Automatic Verification of Timed and Hybrid Systems
  Rajeev Alur (AT&T Bell Laboratories, USA)

     Traditionally, the focus of the research in formal methods has been
qualitative temporal reasoning about behaviors of communicating processes.
The decision to abstract away from quantitative time has had many
advantages, but it is inadequate when reasoning about embedded systems that
must interact with physical processes; the correct functioning of the
control systems in devices from thermostats to airplanes depends crucially
upon the continuous parameters. Consequently, in recent years there has been
extensive research in developing methods for specification and verification
of such embedded systems. This tutorial provides a selective sampling of
modal logics and finite automata that admit automatic verification of
real-time and hybrid systems.  In the first part, we show how the model of
transition systems can be augmented to model the behavior of real-time
systems. Then we consider possible extensions of temporal logics to specify
correctness requirements concerning timeliness.  The model-checking problem
is, then, to verify that a finite-state real-time system satisfies its
specification given in timed temporal logic. We outline the basic
algorithmic techniques needed to solve this problem, and survey the known
complexity and decidability results.  In the second part, we consider
different heuristics to improve efficiency of the model-checking problem. In
particular, we consider an iterative solution that incorporates the
specified timing constraints in the model in an incremental fashion. This
solution is implemented in the AT&T verifier COSPAN, and we discuss our
experiences with the tool.  The last part of the talk shows how the
specification and verification methods generalize to hybrid systems, systems
comprising a discrete program embedded in a continuously changing environment.
Coffee break:  16h30-17h00

Tutorial:  17h00 - 20h00
Formal Methods for the Synthesis of Discrete Event Systems
  A. Khoumsi and K. Saleh (Universite de Montreal, University of Kuwait, Kuwait)

     The aim of this tutorial is to present some formal and systematic
methods for designing Discrete Event Systems (DES). DESs arise in the domain
of computer networks and communication protocols, and also in other domains
such as flexible manufacturing, robotics, process control. Two major
approaches to the design of such systems are: Analysis and Synthesis.  The
latter is the main topic of this tutorial. Contrary to the analytic
approach, the synthetic approach consists of proposing direct methods which
do not require any further verification activities: the synthesized system
is correct by construction. The tutorial is divided into three parts.  The
first part provides a survey and assessment of existing synthesis methods.
The second part presents two relatively new synthesis methods. The first
method has been developed for designing protocols for applications with
temporal requirements. The second method has been developed for designing
protocols using an approach inspired from the control theory of DESs.  The
third part proposes a more general and hybrid approach for designing DESs.
It consists of combining the synthesis and analysis approaches for designing
protocols.

Room 2 - Location:  Salon Le Portage

Tutorial:  (with midmorning coffee)  09h00 - 12h00
Formal design and implementation of high speed multimedia protocols
  Michel Diaz (LAAS du CNRS, France)

     The introductory part of the tutorial presents the general constraints
that exist in distributed multimedia systems. Then the limits of the
networks and the properties of the needed formal approaches will be
given.  The first section gives one formal basis for representing multimedia
synchronization in multimedia objects. This formal model allows one to
represent flow based systems that include nominal, maximal and minimal
durations, and that include temporal delays and jitters.  A few basic models
will be given based on Timed Petri nets, leading to Timed Stream Petri Nets
(TSPN) and hierarchical TSPN.  It will be shown how TSPN can be used for
defining a general basic synchronization inside multimedia objects.  The
second section of the tutorial will present a new solution for designing and
implementing high speed multimedia protocols.  Usual communication protocols
are either connection oriented or connectionless. It will be shown how these
protocols, as UDP and TCP, are a specific case of a more general concept that
will be presented, called a partial order connection. It is then explained
how a partial order connection defines the more adequate transfer protocol
for a specific multimedia information and how this connection is closely
related to the formal TSPN model of the object. It will appear how the most
adequate transfer protocol can be obtained, given a specific multimedia
object, simply by deducing the partial order protocol from the partial order
of the object synchronization.  Finally, the principle of implementing such
a protocol will be given.  Such an implementation is able to handle partial
reliability and partial orders for a set of monomedia connections having
different qualities of service. It will be shown how such implementations
can provide the user with the best delay values and use of resources.

Lunch at the hotel:  12:00 - 13:30  -  Salle a diner Le Castillon

Tutorial:  13h30 - 16h30
High Performance Protocol Architecture
  Walid Dabbous (INRIA de Sophia Antipolis, France)

     The development of high speed networking applications requires efficient 
communication subsystems.  In this tutorial, we will first give a rapid 
historical survey on protocols optimization techniques and on some high speed 
transport protocols developed for specific application needs.  We will then 
show the need for a new protocol architecture based on the "Application Level 
Framing" (ALF) and "Integrated Layer Processing" (ILP) concepts.  ALF states 
that applications send data as a sequence of autonomous "frames", which will be
at the same time the unit of transmission, the unit of control and the unit of 
processing.  This allows for efficient design of application specific protocols.
It also enables ILP i.e. the integration of multiple transmission control 
layers in a single loop, maximizing the efficiency of modern processors.  We 
will present both the architectural design aspects and the corresponding 
implementation problems. Practical experimentation with ALF and ILP will also 
be described and their benefits assessed.  We will finally study how to 
automatically build communication subsystems for multimedia applications
based on this architecture.

Registration:   19h30-21h00  Location:  Salon Le Portage
Cocktail:       19h30-21h00  Location:  Salon Le Portage

CONFERENCE

WEDNESDAY, October 18

Location:  Salon Outremont
Welcoming Remarks:  09h00 - 09h15
Invited Presentation:  09h15- 10h15
Specification and Verification of Timed Systems
  Joseph Sifakis (VERIMAG, France)
Chairperson:  R. Gotzhein (Univ. of Kaiserslautern, Germany)
     We present a survey of recent results on the specification and
verification of timed systems.  Three different classes of formalisms are
considered: Algebraic formalisms including operators that allow to express
timing constraints like delays, timeouts, watchdogs. These formalisms can be
considered as timed process algebras, the most realistic representatives
of which are the timed extensions of the Lotos language. Transition
based formalisms which can be considered as extensions of automata or Petri
nets with timing constraints. This class includes timed Petri nets and
extensions of automata with continuous variables measuring the time elapsed
such as timed automata and hybrid automata. Logical formalisms which are
languages of the formulas of a logic with operators expressing timing
constraints. Representatives of these formalisms are real-time temporal
logics that are extensions of temporal logic with quantitative time and the
Calculus of Duration.  We show that as in the untimed case, all these
formalisms admit a general common model: labeled transition systems with
timed transitions. The existence of a common semantic framework allows a
comparison of the classes. We focus on two particular problems: The
translation of algebraic languages into transition based ones. This is a
central problem for the compilation of algebraic timed languages into an
executable model and it raises problems of compositionality, efficiency and
optimality of the generated model.  The verification by comparison of two
transition-based descriptions or by comparison of a transition based
description against a logical specification. We conclude by discussing
issues concerning the applicability of the existing results and approaches
and by pointing out some interesting research directions.

Coffee break:  10h15 - 10h45

Session 1  -  Chairperson:  A. Petrenko (Univ. of Montreal, Canada)
Design Methodologies:  10h45-12h15
Distributed System Specification in VDM++, K. Lano (Imperial College, UK)
OMT*, Bridging the Gap between Analysis and Design, K. Verschaeve, B. Wydaeghe,
L. Cuypers, V. Jonckers, J. Heirbaut (VUB-INFO, Belgium)
Formal Support for Design Techniques:  A Timethreads-LOTOS Approach, D. Amyot, 
F. Bordeleau, R. J.A. Buhr, L. Logrippo (Univ. of Ottawa, Canada)

Lunch-Demo at CRIM:  12h15 - 14h30  Buffet and tool demonstrations

Session 2 - Chairperson:  P. Dembinski(Int. of Computer Science, Poland)
Verification I:  14h30 - 15h55
Using Partial-Order Methods for the Verification of Behavioural Equivalences, 
M. Lara de Souza, R. de Simone (INRIA, France)
Formal Verification of a Protocol for Communications over Faulty Channels, 
B. Chetali, P. Lescanne (CRIN-CNRS, France)
Specifying Properties of Basic LOTOS Processes Using Temporal Logic, 
C. Kirkwood (Univ. of Glasgow, UK)
A Reachability Analysis of RT-LOTOS Specifications, J.-P. Courtiat, 
R. C. de Oliveira (LAAS-CNRS, France)

Coffee break:  15h55 - 16h15

Session 3 - Chairperson:  J. Quemada (Univ. polytechnique, Madrid)
Algebraic Languages:  16h15 - 17h30
Towards a mobile LOTOS, E. Najm, J.-B. Stefani, A. Fevrier (ENST, CNET, France)
Type Specifications with Processes, F. Puntigam (Technische Univ. Wien, Austria)
A Unified Model for CSP-like Languages with Specifications, L. Lai (Univ. of 
Bradford, UK)

THURSDAY, October 19

Location:  Salon Outremont
Session 4 - Chairperson:  L. Marshall (BNR, Canada)
System Specification and Z:  9h00 - 10h30
Secrets of Call Forwarding:  A Specification Case Study, P. Zave (AT&T, USA)
Formal Method for Event-triggered Sequential Systems, C. Petersohn (Christian-
Albrechts Univ., Germany)
An Extension of GDMO for Formalizing Managed Objects Behaviour, J. Keller 
(France Telecom, France)

Coffee break:  10h30 - 11h00

Invited Presentation:  11h00 - 12h00
Stabilizing Client/Server Protocols without the Tears
  Mohamed G. Gouda (Univ.  Texas at Austin, USA)
Chairperson:  Y. Hirakawa (NTT, Japan)
     We identify a rich class of client/server protocols.  Each protocol in
this class consists of a client and a server processes that engage in an
infinite sequence of sessions.  Each session consists of a bounded number of
phases, and in each phase, either the client sends a bounded number of
messages to the server, or the server sends a bounded number of messages to
the client.  We discuss a simple method for making each protocol in this
class stabilizing.  The method involves three techniques:  session
identification, session abortion, and session restart.  The resulting
protocols, thanks to their stabilization properties, possess a high degree
of fault tolerance.

Lunch-Demo at CRIM:  12h15 - 14h30 Buffet and tool demonstrations

Session 5 - Chairperson:  R. Groz (CNET, France)
Industrial Experiences:  14h30 - 16h00
Experiences of using SDL collected in IskraTEL SDL Methodology, A. Robnik 
(IskraTEL, Slovenia)
Development of Broadband ISDN Telecommunication Services using SDL'92, ASN.1 
and Automatic Code Generation, U. Behnke, M. Geipl, G. Kurzbach, R. Mundstock, 
R. Schroder (Deutsche Telekom, Humboldt Univ. Germany)
Supporting Evolution of SDL-based Systems:  Industrial Experience, B. Gulla, 
J. Gorman (Norwegian Inst. of Tech. and SINTEF DELAB, Norway)

Coffee break:  16:00 - 16h30

Session 6 - Chairperson: R. Castanet (LABRI, France)
Applying Formal Methods:  16h30 - 17h45
A LOTOS Compiler Generating Multi-threaded Object Codes, K. Yasumoto, 
T. Higashino, K. Abe, T. Matsuura and K. Taniguchi (Osaka Univ., Japan)
A Comparison between the Service Addition Language SAL and the ITU-T 
Recommendation Z.120, S. Some, R. Dssouli, J. Vaucher (Univ. of Montreal, 
Canada)
Combining Formal Methods:  An Exercise in Integration, J.-Ch. Gregoire, 
M. Ferguson, L. Pino (INRS-Telecommunications, Canada)
Formal Specification of a Framework for Synchronous Groupware Development, 
A. Kerbrat, S. Ben Atallah (Bull-IMAG, France)

BANQUET  :  19h30   -   Salons Verdun-Lachine-Lasalle

FRIDAY, October 20

Location:  Salon Outremont
Session 7 - Chairperson:  A. Cavalli (Int, France)
Tools and Testing :  09h00 - 10h00
SELEXPERT - A Knowledge-based Tool for Test Case Selection, A. Guerrouat, 
H. Koenig, A. Ulrich (Otto von Guericke Univ., Germany, Brandenburg Univ., 
Germany, Hong Kong Univ., Hong Kong)
Mutation Analysis Applied to Validate Specifications based on Petri Nets, 
S. Fabbri, J.C. Maldonado, P.C. Masiero, M.E. Delamaro, E. Wong (USP, Brasil, 
Bellcore, USA)
A New Approach for Distributing Estelle Specifications, E. Lallet, S. Fischer, 
J.-F. Verdier (INT, france)

Coffee break:  10h00 - 10h30

Panel  -  Formal Methods after 15 years:  Status and Trends:  10h30 - 12h30

Lunch on your own:  12h30 - 14h00

Session 8 - Chairperson:  H. Rudin (IBM, Switzerland)
Real-time and Stochastic Systems: 14h00- 15h30
Critical Time Distributed Systems:  Qualitative and Quantitative Analysis 
Based on Stochastic Timed Petri Nets, G. Juanole, L. Gallon (LAAS-CNRS, France)
Testing Semantics for Probabilistic LOTOS, M. Nunez, D. de Frutos (Univ. 
Complutense de Madrid, Spain)
Real-time LOTOS and Timed Observations, J. Davies, J. Bryans (Univ. of 
Reading, UK)

Coffee break:  15h30 - 16h00

Session 9 - Chairperson:  R. Tenney (Belmont, USA)
Verification II:  16h00 - 17h30
Assertional Verification of a Connection Management Protocol, A. L. Olah, 
S. M. Heemstra de Groot (Univ. of Twente, Netherlands)
Sharing Trees for "on-the-fly" Verification, F. Gagnon, J.-Ch. Gregoire, 
D. Zampunieris (INRS-Telecommunications, Canada, Facultes universitaires 
Notre-Dame-de-la-Paix, Belgique)
Verification of Liveness Property for Communicating FSM's with Conditional 
Transitions depending on State Visiting Numbers, T. Higashino, A. Nakata, 
T. Itoh, K. Taniguchi (Osaka Univ., Japan)
A New Approach for Protocols Performance Evaluation using Annotated Estelle 
Specifications, M. Hendaz, S. Budkowski (INT, France)

TOOL DEMONSTRATIONS:
     Demonstrations of tools will be provided during the conference.  They 
will be held on Wednesday and Thursday at CRIM (Centre de Recherche 
Informatique de Montreal) during a 2-hour lunch-demo (a little map will be 
provided).

     People interested in demonstrating tools are invited to contact Daniel 
Ouimet at Universite de Montreal ([email-masked]).

LOCATION
Most of the events will be held at the Montreal Hilton Bonaventure Hotel, 
1 Place Bonaventure, Montreal (Quebec), Canada, H5A 1E4 and the demonstrations 
will be held at CRIM, 1801, McGill College, office 800.

CLIMATE
The temperatures in late October range from the average high of 8¡C to the 
12¡C.  Rain showers are possible with, say, 30% probability.  

ATTRACTIONS
The hotel is located in the heart of downtown Montreal, just minutes from 
commercial areas with plenty of animation and more rustic areas with Old World 
charm.  Many visitors have enjoyed the numerous cafes, artists' hang-outs, 
boutiques and fine restaurants, and the district of Old Montreal against the 
backdrop of the St. Lawrence river.  The organizing committee will provide 
special guidance to the better restaurants in the city.  This period of the 
year is the time when the coulored leaves can be admired in  the parcs of 
Montreal and throughout the forests in the area.

RENTING A CAR
We also have a special agreement with some Thrifty locations (Downtown,
Mirabel and Dorval Airport). They give a special rate (unlimited mileage)
to FORTE'95 participants, which is:
-  38$ CAN per day (or 209$ a week) for a Full Size car	(Intrepid Chrysler)
-  37$ CAN per day (or 204$ a week) for a Compact Size car (Neon Chrysler)
-  if you do not have insurance with your credit card, you can get a special
   rate of 10$ CAN per day
Reservations can be made at the conference (see Daniel Ouimet:
[email-masked]) or by phoning in advance Claude Richard at
1-514-498-2899, Monday-Wednesday-Thursday, 9-5 EDT. To pick up your car, you
absolutely need a letter from the organizer of the conference to identify
yourself as a FORTE participant. This letter will be available upon request
at the conference or before, if needed, by asking with your registration.
You do not need a car during the conference (all activities are held
downtown at the hotel), but it could be nice before or after the conference
for some tourist sightseeing.

TRANSPORTATION
Air Canada has been appointed the Official Airline for FORTE'95.  Call Air 
Canada at 1-800-361-7585 or your travel agent today and take advantage of:  
-Special convention rates for travel within North America, 
-Substantial savings with Air Canada and Continental Airlines' joint 
  Convention fares, 
-Aeroplan or OnePass miles that can be redeemed on any Air Canada or 
  Continental route, worldwide, 
-Savings up to 50% on the Regular Economy Class Fares, -Overseas passengers 
  will be offered the best available fare.
* Certain rules and conditions will apply.
When purchasing your ticket, please ask that your Event Number:  CV951464 
be entered in the Tour Code box of your ticket, regardless of the fare 
purchased.

Distance from Dorval Airport to the Montreal Hilton Bonaventure Hotel is less 
than 20 km.  Distance from Mirabel International Airport to the Montreal Hilton
Bonaventure Hotel is 60 km.  The Dorval Airport shuttle to Montreal Hilton 
Bonaventure Hotel (costs 9,00$ CAN, and a taxi approximately 20$ CAN.  The 
Mirabel Airport shuttle to central bus station costs 13,00$ CAN, and a taxi 
approximately 45$.  The name of the shuttle company is Aeroplus (633-1100).  
Montreal Hilton Bonaventure Hotel is about 45 minutes driving from the Mirabel 
International Airport and 20 minutes from Dorval Airport, subject to good 
traffic conditions.

ADVANCED REGISTRATION
Please use a copy of this form to pre-register.  Advanced registration closes 
September 16, 1995. After this date, registration is subject to a late fee.  
Please mail your completed form with cheque (drawn on a North American Bank) 
or money order (in Canadian funds) or your Master card number (with your 
signature) payable to:
FORTE'95
c/o Lucie Levesque
Departement d'informatique et de recherche operationnelle
Pavillon Andre Aisendstat
Universite de Montreal
2900, blvd. Edouard-Montpetit (2219), Montreal, (Quebec), Canada, H3T 1J4
Tutorial registration fee covers: Attendance of tutorials, tutorial notes,  
lunch and coffee breaks on Tuesday, October 17.  Conference registration fee 
covers:  Conference admission, proceedings, reception on Tuesday night, lunches
(except Friday), coffee breaks and the conference banquet dinner.
Full and Student registrations fees cover:  same as tutorial plus conference 
admission.
Requests for refunds will be honoured until September 1, 1995.  
For further info. please contact Lucie at:  (email):  [email-masked]
(phone) (514) 343-6111, extension 3520 or (fax) (514) 343-5834.

FORTE'95 Registration Form
Family name     
Given name      
Affiliation     
        
Address         

Postal code                             Country         
Phone number            
e-mail          
                  before Sept. 16        after
Conference                550             600
Tutorial                  300             350
Full                      750             800
Student (1)               300             350
Additional banquet tickets 75              75
Extra proceedings          50              50
Total fee in canadian currencies   ___________________
(1)  Please attach proof of student status

by ______ credit card (Master Card only)

Name on credit card: _________________________
Credit card number: _________________________
Expiration date: _____________________________
Authorized signature: ________________________
Signing date: _______________________________

by ______ cheque drawn to a North American bank.

by ______ money order in canadian currencies to FORTE'95

If you cancel, we must receive your cancellation by mail, 
fax or e-mail by September 1, 1995.

HOTEL RESERVATION
A block of rooms has been reserved for the FORTE'95 participants.  Please 
mention that you are part of FORTE'95.  Reservations* must be received by 
September 16, 1995.  Reservations should be confirmed with either a check 
covering the first night's stay, or by any major credit card.  The conference 
rate at the Hilton Bonaventure is $129.00 CAN (single or double occupancy). 
There is a charge of $25.00 per extra person up to a maximum of four (4)**.  
All rates are net, although the 7% goods and services tax (GST) is refundable 
to non-Canadian residents.  Check-in time is 15h00 and check-out time is 
12h00 noon.

FORTE'95 Hotel Reservation Form
Family name     
Given name      
Affiliation     
Address         

Postal code                              Country        
Phone number    
Arrival date/time __________________________
Single or double        
or Credit card          
Card No.        
Expiry date     
Signature       

**  If 3 persons share a room, it will cost 129$ + 25$ = 154$ divided 
    by 3 persons = 52,00 $ per person per night
**  If 4 persons share a room, it will cost 129$ + 50$ = 179$ divided 
    by 4 persons = 44,75 $ per person per night

*   Please call, write or fax your reservation directly at the Montreal 
    Hilton Bonaventure Hotel, 1, place Bonaventure, Montreal, Quebec 
    Canada, H5A 1E4.
    International toll-free tel.:  1-800-445-8667
    Tel.:  1-514-878-2332
    Fax.:  1-514-3881

===========================================================================

-- 
Daniel Ouimet	Pavillon Math-Info, bureau 2227	[email-masked]
Universite de Montreal, Dept. IRO. C.P. 6128, succursale Centre-Ville
Montreal (Quebec) H3C 3J7, CANADA
(514) 343-6111 ext. 3506        FAX: (514) 343-5834