MATCH Advanced Summer Schools (LAST ANNOUNCEMENT)
Gabriele Kotsis
gabi@poseidon.ani.univie.ac.at
Tue, 30 Jun 1998 10:37:11 +0200
Bitte, auch/insbesonders an interessierte Studierende weiterleiten!
Last announcement (Application: before July 1st, 1998)
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*********************************
* MATCH ADVANCED SUMMER SCHOOLS *
*********************************
______________________________________________________________________
| |
| Performance Models for Discrete Event Systems with Synchronizations: |
| Formalisms and Analysis Techniques. |
| |
| September 3-11, 1998. Jaca, Spain |
|______________________________________________________________________|
______________________________________________________________________
| |
| System Engineering. A Petri Net Based Approach |
| to Modelling, Verification and Implementation. |
| |
| September 14-22, 1998. Jaca, Spain |
|______________________________________________________________________|
All the details can be found on the Schools www page
http://www.cps.unizar.es/deps/DIIS/MATCH/
*************************************************************************
GENERAL PRESENTATION
MATCH (Modelling and Analysis of Time Constrained and
Hierarchical Systems) is a Human Capital and Mobility
initiative, sponsored by the European Union. One of its
objectives is the organisation of two open
complementary Advanced Schools concerning Discrete
Event Dynamic Systems (DEDS), focusing one on
performance modelling and evaluation, and the other on
modelling and verification. Each school can be attended
independently.
The intended audience consists of people interested in
both the theoretical and practical aspects of modelling
for evaluation and verification of DEDS. Concepts,
methods and computer supported tools will allow us to
provide answers to questions like the following:
o Could a token-ring protocol lose or duplicate some
messages?
o How to increase the throughput of a large
insurance company by a work flow analysis?
o Is it possible to check whether a flexible
manufacturing system may have some of its robots
blocked?
o How should a production line be designed in order
to achieve a given production rate?
o What should be the size of the buffers of ATM
switches so that the cell loss probability remains
below a given value?
o Do the verification and the performance evaluation
need completely different formalisms?
o What kind of approaches are available to deal with
large size and complex DEDS?
*************************************************************************
PARTICIPATION
Both Advanced Schools will take place at the Residence
of the University of Zaragoza in Jaca (in the Pyrenees
mountains), where International Summer Courses are
being organised since the beginning of this century
---mostly on humanistic studies. Participation is
limited to 40 students per School.
The registration fee and full board lodging is:
o 100.000 pesetas for one school (10 days) and
o 170.000 pesetas for both schools (20 days).
A small number of grants will be available. Those
wishing to apply for a grant should send a letter of
explanation, a curriculum vitae and a letter of
recommendation from a major advisor before June 1st,
1998.
Participants in each school will receive copies of the
lecture transparencies and the draft of a book covering
the topics of the corresponding school in detail. Full
lodging will be provided (in double rooms) at the
Residence, where all the classes will also take place.
A transport service Zaragoza-Jaca and return will also
be provided. Interesting cultural and sightseeing
excursions are planned.
Laboratories will be organized throughout the schools
to provide the students with practical experience on
the application of the formalisms to concrete examples
and case studies. Several computer tools will be
available.
*************************************************************************
Performance Models for Discrete Event Systems with
Synchronizations: Formalisms and Analysis
Techniques.
September 3-11, 1998. Jaca, Spain.
Scientific Directors:
G. Balbo and M. Silva
-------------------------------------------------------------
Aims and Scope
Discrete Event Dynamic Systems (DEDS) are based on a view of
dynamic systems where discrete states and events play a
fundamental role. DEDS are becoming increasingly interesting
as the importance of automation and control grows in modern
technology. Application domains like manufacturing,
transport or telecommunication use extensively concepts and
techniques from DEDS. Design optimization, scheduling
(performance control), monitoring, implementation (possibly
fault-tolerant),... are among the critical issues that
require the use of modelling and of qualitative and
quantitative analysis techniques.
Formal methods for the specification, verification and
performance evaluation of DEDS are becoming more and more
important as systems increase in size and complexity. The
aim of this Advanced School is to present a comprehensive
Petri Net-based framework to model and analyze the
performance of complex distributed systems in which the
interplay of concurrency and cooperation among agents is
crucial at the global system level and in which queueing,
service, routing, and synchronization (e.g. rendez-vous,
capacity constraints,...) are equally important. Other
formalisms, like Queueing Networks and Stochastic Process
Algebras, will be also considered and discussed from the
point of view of their relations with Stochastic Petri Nets.
The interleaving of qualitative and quantitative analysis of
complex DEDS will be stressed.
The most important aspects of net based performance
modelling and analysis techniques will be presented to train
the participants in the effective use of formal models in
existing and possible future application domains.
-------------------------------------------------------------
Intended Audience
People interested in performance evaluation of DEDS
through modelling. The material and the lectures of the
school will be organized in such a way that the
following two, complementary, type of audience can
profit from the school:
o people with a background in performance evaluation
willing to deepen their knowledge on performance
modelling through a Petri net based approach to the
problem,
o people with a background in untimed Petri Net
theory (or alternative formalisms, like Process
Algebras) willing to explore the use of the
formalism for performance evaluation.
Special introductory lectures will be given to provide a
common basic background for all the participants.
-------------------------------------------------------------
Topics and Lecturers
1. Formalisms (Queueing Networks, Untimed Petri Nets,
Stochastic Petri Nets, Untimed and Stochastic Process
Algebras,...);
2. Modelling techniques and methods: (running) examples
and case studies.
3. Properties and Qualitative Analysis (basic logical
properties, Place-Transition and Colored net
correctness analysis, performance indices and
qualitative properties);
4. Discrete-Event Simulation (centralized schemas,
synchronous and asynchronous parallel/distributed
simulation);
5. Markov Chain Generation (bounded Markovian models,
one-place unbounded Markovian models, non-Markovian
models);
6. Net-driven Markov Chain generation (decomposition and
tensor algebra approach, symmetries and
quasi-symmetries, combining decomposition and
aggregation, periodic ordering);
7. Net-driven Analytical Methods (PNs and product forms,
linear programming and performance bounds);
8. Approximate Net-Driven Decomposition Methods
(product-form approximation, response-time
approximation,...)
The lecturers are well-known experts in modelling and
performance evaluation of DEDS. They are involved in
theoretical and applied research and are also collaborating
with industry. They include:
G. Balbo (Torino), B. Baynat (Paris), J. Campos (Zaragoza),
G. Chiola (Genova), Y. Dallery (Paris), S. Donatelli
(Torino), C. Dutheillet (Paris), A. Ferscha (Vienna), G.
Franceschinis (Torino), S. Haddad (Paris), B. Haverkort
(Aachen), U. Herzog (Erlangen-Nuremberg), J. Hillston
(Edimburgh), M. Ribaudo (Torino), M. Sereno (Torino), M.
Silva (Zaragoza), E. Teruel (Zaragoza)
Application domains
* Manufacturing
* Transport
* Telecommunication
* Concurrent architectures
* Concurrent programming
Tools
* GreatSPN (GRaphical Editor and Analyzer for Timed and
Stochastic Petri Nets). A software package for the
modeling, validation, and performance evaluation of
distributed systems using Generalized Stochastic Petri
Nets and their colored extension: Stochastic
Well-formed Nets. The tool provides a friendly
framework to experiment with timed Petri net based
modeling techniques. It implements efficient analysis
algorithms to allow its use on rather complex
applications, not only toy examples.
* SPN2MGM. A tool for specifying stochastic Petri Nets of
which the underlying Markov chain can be solved using
matrix-geometric methods.
* Stochastic Process Algebras, such as TIPP or PEPA are
compositional specification formalisms discussed within
the performance school. The TIPPtool aims at realising
all beneficial aspects of compositional performance
modelling. It incorporates methods for compositional
specification as well as solution, based on
state-of-the-art-techniques, and wrapped in a
user-friendly graphical front end.
-------------------------------------------------------------
Detailed Programme of the Performance Models Summer School
Day Session Title Professors Hours
Thursday a.m. General presentation M. Silva 30m.
3rd (*) Basics on stochastic
models and QN's (lecture) Y. Dallery 2h.
(**) Basics on PN's (lecture) E. Teruel 2h.
Untimed PN's (lecture) M. Silva 1h.
p.m. Timed and stochastic Petri
nets (lecture) G. Chiola
1h.30m.
Examples and exercises G. Chiola 1h.
Friday 4th a.m. Logical properties of P/T nets
(lecture) M. Silva 2h.
Performance measures (lecture) J. Campos
1h.30m.
p.m. Bounded GSPN's (lecture) G. Balbo 2h.
Introduction to tools (lecture
and exercises) S. Donatelli 30m.
Saturday a.m. Tools and exercises S. Donatelli 1h.
5th Well Formed Nets (lecture)
G.Franceschinis1h.30m.
Tools and exercises G. Franceschinis1h.
p.m. Analysis of WFN's (lecture) C. Dutheillet 2h.
Overview of analysis
techniques (lecture) G. Balbo 30m.
Sunday 6th FREE/EXCURSION
Monday 7th a.m. Stochastic process algebras
(lecture) J. Hillston 2h.
Compositionality in
SPA's/SPN's (lecture) H. Hermanns
1h.30m.
p.m. Comparison QN's/SPN's
(lecture) G. Chiola 1h.
Simulation (lecture) A. Ferscha
1h.30m.
Tuesday 8th a.m. Stochastic WFN (lecture and
exercises) G. Franceschinis30m.
Exploiting symmetries
(lecture) G. Franceschinis1h.
Exploiting compositionality
(lecture) S. Donatelli 2h.
p.m. Distributed (asynchronous)
simulation (lecture) A. Ferscha 1h.
Distributed (synchronous)
simulation (lecture) A. Ferscha
1h.30m.
Wednesday a.m. Combining composition and
9th aggregation (lecture) P. Moreaux 2h.
Performance bounds (lecture
and exercises) J. Campos
1h.30m.
p.m. FREE/EXCURSION
Thursday a.m. General approach to
10th decomposition based
approximation methods Y. Dallery 1h.
(lecture)
Approximation methods I
(lecture) B. Baynat 1h.
Non-exponentially timed nets
(lecture) G. Balbo
1h.30m.
p.m. One place unbounded SPN's
(lecture) B. Haverkort
1h.30m.
Product form solutions I
(lecture) M. Sereno 1h.
Friday 11th a.m. Product form solutions II
(lecture) M. Sereno
1h.30m.
Approximation methods II
(lecture) J. Campos 1h.
Epsilon-symmetries (lecture) G. Franceschinis1h.
Closing session
(*) People with some background on PN's.
(**) People with some background on stochastic models and QN's.
*************************************************************************
System Engineering. A Petri Net Based Approach to
Modelling, Verification and Implementation.
September 14-22, 1998. Jaca, Spain.
Scientific Directors:
C. Girault and R. Valk
-------------------------------------------------------------
Aims and Scope
Formal methods for the specification and verification of
hardware and software systems are becoming more and more
important as systems increase in size and complexity. The
aim of the school is to illustrate progress in formal
methods, based on the Petri net formalism, through a
collection of examples arising from Flexible Manufacturing,
Telecommunication and Workflow Management Systems.
The scope of the school covers several of the main phases of
the life cycle of the design and implementation of a system:
specification, model checking techniques for verification,
analysis of properties, code generation, and execution of
models. The presentation describes these techniques and
their tool support. It identifies and explains fundamental
concepts like composition, abstraction, and reusable models;
model verification and verification of properties. Practical
work with tools will play an important role.
-------------------------------------------------------------
Intended Audience
People interested in the application of Petri nets to
systems engineering. The material and the lectures of the
school will be organized in such a way that the following
two groups of people can benefit from this course:
* People interested in the application of Petri nets.
The course starts with a general introduction to
Petri nets and focuses on the application of Petri
nets to three application domains: workflow
management, telecommunication and flexible
manufacturing.
* People interested in the relations between theory
and practical use of Petri nets.
The course addresses fundamental modeling problems
and analysis techniques. State-of-the-art analysis
techniques are presented for people interested in
the verification of complex systems.
The course will bring together practitioners, researchers
and PhD students interested in Petri nets. Cases and
concrete projects are used to create a stimulating
atmosphere. People attending the course will be trained
in the use of several computer tools.
-------------------------------------------------------------
Topics
1. Basic Concepts of Petri nets (place transition nets,
high level nets, examples).
2. Modelling techniques and methods: (running) examples
and case studies (from Flexible Manufacturing,
Telecommunication, Workflow Systems,...).
3. Tools for Petri nets (presentations and examples).
4. High Level Petri nets (syntactical aspects,
parametrization).
5. Properties, Analysis and Verification (safeness and
fairness properties,...; structural properties and
subclasses of nets).
6. Petri nets in specific application domains
(Manufacturing systems, workflow systems,
telecommunication systems).
7. Advanced topics in Analysis and Verification (State
space based and structural methods).
The lecturers are well known experts in modelling and
verification of DEDS. They are involved in theoretical and
applied research and are also collaborating with industry.
They include:
W. v.d. Aalst (Eindhoven), J.M. Colom (Zaragoza), P.
Estrailler (Paris), J. Ezpeleta (Zaragoza), B. Farwer
(Hamburg), C. Girault (Paris), S. Haddad (Paris), J.M.
Ili (Paris), F. Kordon (Paris), D. Poitrenaud (Paris),
M.O. Stehr (Hamburg), E. Teruel (Zaragoza), R. Valk
(Hamburg), M. Voorhoeve (Eindhoven).
-------------------------------------------------------------
Parts of the course
1. Introduction to Petri Nets
2. Applications
1. WorkFlow Management Systems
2. Flexible Manufacturing Systems
3. Formal Design of Telecommunication Services
3. Advanced topics in Analysis and Verification
1. Prototyping
2. State Space Methods
3. Structural Methods
4. Deductive Methods
4. Tools
1. Introduction to Petri Nets
In the past years an increasing demand for precise and graphical
modelling techniques has become visible in almost all fields of
computer applications from industry, commerce and research.
This is due to growing requirements for efficient and reliable
methods on the one hand and increased power of computer tools
on the other.
It is thus not surprising that Petri nets have become a common
technique for the specification, validation and performance
evaluation of systems, since they provide an intuitive approach,
formal techniques and graphical description methods.
In the introduction (of the summer school) participants will be
trained into all these features, starting from a very basic level up
to rather sophisticated skills. This will be possible by means of an
integrated approach, combining lectures, classroom exercises and
computer sessions with Petri net tools.
The introduction will start with a general and intuitive notion of Petri
nets and the general principles behind them. Then, an informal tutorial
will introduce the basic models of place/transition nets and high level
nets, leading to different formal representations to be used in computer
tools.
For applications to systems analysis and verification, powerful
mathematical methods, like linear programming, will be employed to
verify correctness properties like safeness, liveness and reachability.
After the first two days the participant will be prepared to enter the
lessons on particular applications.
2. Applications
2.1 WorkFlow Management Systems
The phenomenon of workflow management will have a tremendous impact on
the next generation of information systems. As the workflow paradigm
continues to infiltrate organizations that need to cope with complex
administrative processes, the WFMS will become a fundamental building
block. Therefore, the subject workflow management is of utmost
importance for people involved in the (re)design of administrative
processes or the development of systems to
support these processes. The Petri net formalism provides a firm
theoretical basis for the modeling and analysis of workflow processes.
The course addresses the following subjects: workflow management
concepts,
architecture of workflow management systems, mapping workflow concepts
onto Petri nets, organizational modeling, verification, and performance
analysis of workflows.
2.2 Flexible Manufacturing Systems
The design and control of Flexible Manufacturing Systems (FMS) is a very
complex task: many different elements have to be combined, and many
different aspects must be taken into account. This complexity has raised
the need of use of formal models in order to represent and validate the
system.
Petri nets are a family of models well suited for the domain: easy
representation of concurrency and competition relations, application of
different desing strategies, ability to generate code in an automatic
way, a well defined semantics applicable for the qualitative and
quantitative analysis and a nice graphical user interface.
The aim of the course is to show how Petri nets can be used for the
modeling and analysis of Flexible Manufacturing Systems (focusing
mainly in qualitative aspects).
2.3 Formal Design of Telecommunication Services
Formal modelling is a key for verification and evaluation of
telecommunication systems. Our application concerns a Multi-Agent System
of contract monitoring. The application acts in the context of the
electronic market. We use a new object-based formalism, which integrates
the principles of the ODP standard. We transform these high-level
formalisms into the uniform high level Petri net formalism while
retaining the original system semantics. The CPN-AMI tools will support
the modelling and the analysis of this application.
3. Advanced topics in Analysis and Verification
Systems will inevitably grow in scale and functionality. Therefore, the
likelihood of subtle errors is also increasing. A first goal of system
engineering is to take advantage of the investment in modelling to
generate a prototype of the system, and to have an implementation
consistent with the validated model. A second goal is to provide
mathematically based methods and tools for verifying such systems.
There exists a diversity of verification methods developed for Petri
nets. This part of the school aims to clarify the bases for choosing an
adequate method for each problem, by discussing issues involved in
the design and the application of each method: 1) Net models that
the method is able to verify; 2) Kinds of properties to check;
3) Families of methods; 4) The interplay of different methods.
3.1 Prototyping
Emphasis will be put on the presentation and discussion of a way to
produce a distributed application from a Petri Net specification.
The produced application is not a Petri net simulation and can be
integrated in a complex execution environment.
3.2 State Space Methods
Efficient methods for the construction of the state space are presented
in this tract. Several verification methods working on the state space
are analyzed and compared.
3.3 Structural Methods
The use of the net structure for formal verification of net properties
is presented. Structural reduction of nets, linear algebra based
techniques, and graph based techniques for net subclasses are the
main topics.
3.4 Deductive Methods
In this tract the use of logics for formal verification of net
properties is presented. Linear Logic enriched by algebraic
specifications leads the way to rewriting logic semantics for algebraic
Petri nets. For verification of
temporal properties of high-level nets a UNITY-style logic is employed.
4. Tools
CPN-AMI is a Petri Net based CASE environment that will be used in the
practical tasks and exercises of the school. It offers a set of services
to ease the work of designers who specify a system by means of the Petri
net theory and benefit from it. It relies on the Macao graph Editor
which
also behaves as the User Interface of CPN-AMI. This software tool runs
on
Sparc/SunOS (4.1.4 or later) Sparc/Solaris (2.4 or later) and
UltraSparc/Solaris (2.5.1 or later).
CPN-AMI is a project initiated in 1987 by Professor C.Girault in the
team "Systmes rpartis et coopratifs", in the Laboratoire d'Informatiques
de
Paris 6 (Previously MASI) in the Universit Pierre & Marie Curie, Paris
(France).
The following tools will be used during the course on Workflow
Management Systems to demonstrate the application of Petri-net-based
software to this domain and which preferably could be used by the
students for doing assignments:
* Woflan (Eindhoven University of Technology) for the verification of
workflow processes made with COSA of PROTOS.
* COSA BPR-toolkit (Software Ley) The design part of one of the
leading European workflow products.
* PROTOS (Pallas Athena) An easy-to-use BPR tool based on Petri nets.
* ExSpect (Bakkenist) To simulate workflow processes made with COSA
of PROTOS.
-------------------------------------------------------------
Detailed Programme of the Systems Engineering Summer School
Day Session Title Professors Hours
Monday 14th a.m. Models and toy examples
(lecture) R. Valk 3h.30m.
p.m. Tools presentation and use of
toy examples (lecture and R. Valk and 2h.30m.
exercises) LIP6
Tuesday a.m. More on High Level Nets
15th (lecture) C. Girault 1h.
More on properties, linear
properties and net subclasses J.M. Colom 2h.
(lecture)
p.m. Modelling process (lecture) M. Voorhoeve
1h.30m.
Principles and tools for
modelling (lecture and M. Voorhoeve 1h.
exercises)
Wednesday a.m. Workflow Management Systems
16th (lecture and exercises) W.v.d. Aalst
3h.30m.
p.m. FREE/EXCURSION
Thursday a.m. Flexible Manufacturing Systems
17th (lecture and exercises) J. Ezpeleta
3h.30m.
p.m. State Space based Methods I J.M.Ilie,
(lecture and exercises) S.Haddad,
2h.30m.
D.Poitrenaud
Friday 18th a.m. Formal Design of
Telecommunication Services P. Estrailler
3h.30m.
(lecture and exercises)
p.m. State Space based Methods II J.M.Ilie,
(lecture and exercises) S.Haddad,
2h.30m.
D.Poitrenaud
Saturday a.m. Structural Methods I (lecture
19th and exercises) J.M. Colom
3h.30m.
p.m. Deductive Methods I (lecture) B.Farwer,
M.O.Stehr
1h.30m.
Parallel Laboratory Sessions on
Work Flow Management Systems,
Flexible Manufacturing Systems -
1h.30m.
and Telecommunication Systems
Sunday 20th FREE/EXCURSION
Monday 21th a.m. Deductive Methods II (lecture B.Farwer,
and exercises) M.O.Stehr
3h.30m.
p.m. Structural Methods II E. Teruel
1h.30m.
Parallel Laboratory Sessions on
Work Flow Management Systems,
Flexible Manufacturing Systems -
1h.30m.
and Telecommunication Systems
Tuesday a.m. Prototyping (lecture) F. Kordon 2h.
22th Work Flow Management Systems
(lecture) W.v.d.Aalst 45m.
Flexible Manufacturing Systems
(lecture) J. Ezpeleta 45m.
p.m. Telecommunication Systems
(lecture) P. Estrailler 45m.
Perspectives and concluding
remarks - 1h.
Discussion and clossing - 45m.
*************************************************************************
REGISTRATION
Applicants should fill in the attached application
form and return it
* by fax to +34.976.762111
* by regular mail to
Prof. M. Silva
Departamento de Informtica e Ingeniera de
Sistemas
Centro Politcnico Superior de Ingenieros
Universidad de Zaragoza
c/Mara de Luna, 3
E50015 Zaragoza, Spain.
before July 1st, 1998.
Accepted applicants are liable to pay the following
registration fee before July 31th, 1998:
* Students participating in one school:
o Total fee (full board included plus
eventual transport from Zaragoza to Jaca
and return): 100000 pesetas (ie. approx.
650 USDs, 1190 DM, 4000 FF, 1170000 liras,
400 GBP).
o Granted students should pay only 60 per
cent: 60000 pesetas (ie. no free access to
the course and, just symbolically, under
of his direct comsumptions).
* Students participating in both schools:
o Total fee:170000 pesetas.
o Granted students: 130000 pesetas
International Money Transfer in pesetas to (send
also information of the transfer from your Bank by
fax to +34.976.762111):
Caja de Ahorros de la Inmaculada
Account No.: 2086 0011 48 07 00 2510 77
Att.: OTRI - MATCH
Agencia No. 11
c/Gran Via, 52
E50005 Zaragoza, Spain
A confirmation of the transfer will be send after
receiving and a receipt will be given at the school.
-------------------------------------------------------------
IMPORTANT DATES
Application: before July 1st, 1998
Payment of registration fee: before July 31th, 1998.
*************************************************************************
MATCH Advanced Summer Schools
Application Form
O Mrs O Ms O Mr
Last Name ..................... First Name .....................
Mailing address and e-mail: ....................................
................................................................
................................................................
................................................................
................................................................
Highest university degree obtained: ............................
Present professional position: .................................
Institute or company presently affiliated with: ................
Current interests: .............................................
I wish to apply for the following (check one):
O Performance Models School (100000 pesetas)
O Systems Engineering School (100000 pesetas)
O Both Schools (170000 pesetas)
O I wish to apply for a grant (letter of recommendation, etc.
enclosed). I O would O would not be prepared to pay
the full fee in case I will not receive a grant.
Payment
If accepted for participation, I will pay my fee, which includes
registration and lodging, before July 31, 1998.
Signature ..................... Date ................
*************************************************************************
ORGANISING COMMITTEE
Members of the Organising Committee from the
University of Zaragoza: M. Silva, J. Campos, J. M. Colom,
J. Ezpeleta, E. Teruel.
For further details please contact:
Prof. M. Silva
Departamento de Informtica e Ingeniera de Sistemas
Centro Politcnico Superior de Ingenieros
Universidad de Zaragoza
c/Mara de Luna No. 3
E50015 Zaragoza, Spain.
e-mail: Match.Schools@posta.unizar.es
*************************************************************************
JACA (Huesca, Spain)
Jaca is the beautiful capital of a region, the Jacetania,
and belongs to the Comunidad Autonoma ("autonomous
community") of Aragon, northeastern Spain. Situated in
the center of the Pyrenees mountains, on the plateau on
the southern bank of the Aragon River, just south of the
French border, Jaca is close to the "Ordesa National
Park" (the oldest protected natural park in Spain, with a
surface area of about 2,200ha.) and several 3000 meters
high mountains, like "Monte Perdido".
Of ancient origin, the city was captured by the Romans in
194 BC and surrounded by walls, which, with medieval
additions, still partly stand. In 716 it was taken by the
Moors and, under the name of Dyaka, was one of the
principal cities of the region governed from Sarakosta
(modern Zaragoza). Retaken by the Christians in 760, Jaca
was declared a "city" by King Ramiro I of Aragon
(1035-63) and was the first capital of kingdom of Aragon.
Jaca has notable landmarks that include the 11th-century
cathedral; the Citadel (Ciudadela), begun in 1593 and in
a state of perfect preservation; and the town hall in
Plateresque style (1544). The Torre del Reloj ("Clock
Tower") is the permanent site of the Comunidad de Trabajo
de los Pirineos, a groupement of three French Regions
(Aquitaine, Languedoc-Roussillon et Midi-Pyrenees ), four
Spanish Comunidades Autonomas (Aragon, Catalunya, Navarra
y Pais Vasco) and the state of Andorra. In odd-numbered
years, Jaca holds the International Folklore Festival of
the Pyrenees, which takes place around the first week of
August. Apart from folklore groups from the
French-Spanish Pyrenees and from different Spanish
provinces, the most outstanding folklore groups from many
countries of the five continents participate, which is
why it has been called the Folklore Olympics. In Jaca it
is possible to go ice-skating in the Palacio de Hielo.
Jaca's economy is based primarily on agricultural trade
and tourism. Pop. is around 12,000.
*************************************************************************
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