Relating Inter-Agent and Intra-Agent Specifications

215 Pages·2012·2.24 MB·English

Facult¶es Universitaires Notre-Dame de la Paix, Namur
Institut d’Informatique
Relating Inter-Agent and
Intra-Agent Speciflcations
The Case of Live Sequence Charts
Yves Bontemps
Th(cid:181)ese pr¶esent¶ee en vue de l’obtention du titre de
Docteur en Informatique .

Jury: Prof. Jean-Luc Hainaut, FUNDP, (Pr¶esident),
Prof. Wolfgang Thomas, RWTH Aachen.
Prof. Sebastian Uchitel, Imperial College London.
Prof. Pierre-Yves Schobbens, FUNDP, (Promoteur).
Prof. Patrick Heymans, FUNDP.

Abstract
The problem of relating inter-agent and intra-agent behavioral speciflcations is
investigated. Thesetwoviewsarecomplimentary, inthattheformeriscloserto
scenario-based user requirements whereas the latter is design-oriented. We use
a graphical, user-friendly and very simple language as inter-agent speciflcation
language: Live Sequence Charts (LSC). LSC is presented and its properties
are investigated: it is highly succinct, but inexpressive. There are essentially
two ways to relate inter-agent and intra-agent speciflcations: (i) by checking
that an intra-agent speciflcation is correct with respect to some LSC specifl-
cation and (ii) by automatically constructing an intra-agent speciflcation from
an LSC speciflcation. Several variants of these problems exist: closed/open
systems and centralized/distributed systems. We give ine–cient but optimal
algorithms solving all problems, besides synthesis of open distributed systems,
whichweshowisundecidable. Alltheproblemsconsideredaredi–cult,evenfor
a very restricted subset of LSCs, without alternatives, interleaving, conditions
nor loops. We investigate the cost of extending the language with control (cid:176)ow
constructs, conditions, real-time and symbolic instances. An implementation of
the algorithms is proposed. The applicability of the language is illustrated on
a real-world case study.
Keywords: Live Sequence Charts, Scenarios, Reactive Systems, Synthesis,
Realizability, Game Theory, Automata Theory.

CONTENTS 1
Contents
Introduction 5
Context . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1 Preliminaries 12
1.1 Languages and automata . . . . . . . . . . . . . . . . . . . . . . 12
1.2 Temporal Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
1.3 Inflnite games . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
1.4 Computational Complexity . . . . . . . . . . . . . . . . . . . . . 20
1.5 Alternation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2 Scenario-based Languages: a Walkthrough 28
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.2 Message Sequence Charts . . . . . . . . . . . . . . . . . . . . . . 29
2.3 Zave’s Sequence Diagrams . . . . . . . . . . . . . . . . . . . . . . 39
2.4 Use Case Maps . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
2.5 Genetic Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
2.6 Live Sequence Charts . . . . . . . . . . . . . . . . . . . . . . . . 51
2.7 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
3 Live Sequence Charts 56
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
3.2 Language Deflnition . . . . . . . . . . . . . . . . . . . . . . . . . 56
3.3 Expressiveness and Succinctness . . . . . . . . . . . . . . . . . . 80
3.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
4 Analysis Problems 101
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
4.2 Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
4.3 Use Case Checking and Reflnement . . . . . . . . . . . . . . . . . 107
4.4 Veriflcation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
4.5 Synthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
4.6 Incomplete Approaches . . . . . . . . . . . . . . . . . . . . . . . 140
4.7 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
2 Contents
5 Language Extensions 148
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
5.2 Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
5.3 Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
5.4 Symbolic Instances . . . . . . . . . . . . . . . . . . . . . . . . . . 167
5.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
6 Implementation 174
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
6.2 Writing a Model . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
6.3 Animation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
6.4 Centralized Realizability Checking . . . . . . . . . . . . . . . . . 183
6.5 Incomplete Distributed Synthesis . . . . . . . . . . . . . . . . . . 185
6.6 LTL Formula Generation . . . . . . . . . . . . . . . . . . . . . . 185
Conclusion 187
3
Acknowledgements
This work has been supported by the\Fonds National de la Recherche Scien-
tiflque"through a\Research Fellow Grant"and travel funding, mainly via the
\Centre F¶ed¶er¶e en V¶eriflcation".
IamthankfultoallJurymembers: Prof.Jean-LucHainaut, Prof.Wolfgang
Thomas, Prof. Sebasti(cid:181)an Uchitel, Prof. Patrick Heymans and Prof. Pierre-Yves
Schobbens. IespeciallyexpressmygratitudetoProf.Thomasforhishospitality
during my stay in Aachen. Prof. Schobbens has been a great advisor. His
insights on the topic of my thesis were very valuable. His intuitions about
forthcoming results were almost always correct, which avoided us to err in
wrong directions but also obliged me to double-check every result we obtained,
just in case (and when they were correct, he could just say\didn’t I tell you
this would be so?").
Sincemyveryflrststepsinresearch,IhavecloselycollaboratedwithPatrick
Heymans. This was a grand experience. Patrick is a psycho proofreader: he
annotates every paper he can get his hands on, until the paper turns into some
kind of red-coloured cubistic painting. As an author, this is a most depressing
experienceasittransformsan\almostperfectpaper"into\almostapaper". But,
as a colleague and co-author, Patrick is also a continuous source of motivation
and inspiration. Our collaboration was very fruitful and I thank him for this.
When my research was stuck and new results did not want to appear, I
have been lucky enough to meet people who showed me the right direction to
proceed. In particular, the initial idea for an algorithm solving merciful games
is due to Dr Christof L˜oding. Prof. Salvatore La Torre referred me to the
PSPACE-hard problem I had to reduce from in order to show most complexity
lower bounds appearing in this thesis. Ironically enough, the proof was in the
very book I had been struggling with for months...but I was just not looking
at the right chapter.
I would also like to thank my colleagues for the great time I had sharing an
o–ce with them: Micha˜el Petit, a serious-minded, austere and selflsh person
whocan’tstandmenconversations;GermainSaval,withhisunbearableBelgian
accent and his total lack of culture, and Jean-Christophe Trigaux, a cofiee-
addict who has no sense of humour and despises sharing anything about his
own research. Thank you also to Ga˜etan, Simon, Vincent, Isabelle, Emmanuel,
Pascal, Mama, and all other colleagues I forgot to list.
Finally, my girlfriend has to be thanked for her constant love and support.
With her by my side, these last four years were a nearly painless experience.
In return, I can only dedicate her this very manuscript, the result of all the
evenings I spent working on my computer. This is objectively a poor gift, but
she will understand how much it represents to me. To Roxane, with all my
gratitude and love.
4 Acknowledgements