This book constitutes the refereed proceedings of the 12th International Conference on Concurrency Theory, CONCUR 2001, held in Aalborg, Denmark in August 2001.The 32 revised full papers presented together with six invited contributions were carefully reviewed and selected from 78 submissions. The papers are organized in topical sections on mobility, probabilistic systems, model checking, process algebra, unfoldings and prefixes, logic and compositionality, and games.

ETAPS 2002 is the ?fth instance of the European Joint Conferences on Theory and Practice of Software. ETAPS is an annual federated conference that was established in 1998by combining a number of existing and new conferences. This year it comprises ?ve conferences (FOSSACS, FASE, ESOP, CC, TACAS), thirteen satellite workshops (ACL2, AGT, CMCS, COCV, DCC, INT, LDTA, SC, SFEDL, SLAP, SPIN, TPTS and VISS), eight invited lectures (not including those that are speci?c to the satellite events), and several tutorials. The events that comprise ETAPS address various aspects of the system - velopment process, including speci?cation, design, implementation, analysis and improvement. The languages, methodologies and tools which support these - tivities are all well within its scope. Di?erent blends of theory and practice are represented, with an inclination towards theory with a practical motivation on one hand and soundly-based practice on the other. Many of the issues involved in software design apply to systems in general, including hardware systems, and the emphasis on software is not intended to be exclusive.

This book constitutes the refereed proceedings of the 12th International Conference on Concurrency Theory, CONCUR 2001, held in Aalborg, Denmark in August 2001.The 32 revised full papers presented together with six invited contributions were carefully reviewed and selected from 78 submissions. The papers are organized in topical sections on mobility, probabilistic systems, model checking, process algebra, unfoldings and prefixes, logic and compositionality, and games.

ETAPS 2002 is the ?fth instance of the European Joint Conferences on Theory and Practice of Software. ETAPS is an annual federated conference that was established in 1998by combining a number of existing and new conferences. This year it comprises ?ve conferences (FOSSACS, FASE, ESOP, CC, TACAS), thirteen satellite workshops (ACL2, AGT, CMCS, COCV, DCC, INT, LDTA, SC, SFEDL, SLAP, SPIN, TPTS and VISS), eight invited lectures (not including those that are speci?c to the satellite events), and several tutorials. The events that comprise ETAPS address various aspects of the system - velopment process, including speci?cation, design, implementation, analysis and improvement. The languages, methodologies and tools which support these - tivities are all well within its scope. Di?erent blends of theory and practice are represented, with an inclination towards theory with a practical motivation on one hand and soundly-based practice on the other. Many of the issues involved in software design apply to systems in general, including hardware systems, and the emphasis on software is not intended to be exclusive.

This volume presents the proceedings of the Sixth International Joint Conference on the Theory and Practice of Software Engineering, TAPSOFT '95, held in Aarhus, Denmark in May 1995. TAPSOFT '95 celebrates the 10th anniversary of this conference series started in Berlin in 1985 to bring together theoretical computer scientists and software engineers (researchers and practitioners) with a view to discussing how formal methods can usefully be applied in software development.The volume contains seven invited papers, among them one by Vaugham Pratt on the recently revealed bug in the Pentium chip, and 44 revised full papers selected from a total of 147 submissions. In addition the TAPSOFT '95 proceedings contains 10 tool descriptions.

This book constitutes the strictly refereed post-workshop proceedings of the 11th International Workshop on Computer Science Logic, CSL '97, held as the 1997 Annual Conference of the European Association on Computer Science Logic, EACSL, in Aarhus, Denmark, in August 1997.The volume presents 26 revised full papers selected after two rounds of refereeing from initially 92 submissions; also included are four invited papers. The book addresses all current aspects of computer science logics and its applications and thus presents the state of the art in the area.

ICALP { the International Colloquium on Automata, Languages, and Progr- ming { is a series of annual conferences of the European Association for Th- retical Computer Science (EATCS). ICALP'99 was organized by the Institute of Computer Science of the Academy of Sciences of the Czech Republic in - operation with the Action M Agency. Stimulated by the positive experience from previous meetings, the guiding idea of the ICALP'99 organization was to keep and to enhance the idea of a parallel two{track conference with invited plenary talks. Similarly to the two parts of the journal Theoretical Computer Science, Track A of the meeting is devoted to Algorithms, Automata, Complexity, and Games, and Track B to Logic, Semantics, and Theory of Programming. The Program Committee was structured along these same lines. As a further inno- tion, ICALP'99 was coordinated with the European Symposium on Algorithms (ESA'99) in such a way that both conferences took place in the same location with the former immediately followed by the latter. ICALP'99 was the 26th in the series of ICALP colloquia. Previous colloquia were held in Paris (1972), Saarbruc .. ken (1974), Edinburgh (1976), Turku (1977), Udine (1978), Graz (1979), Amsterdam (1980), Haifa (1981), Aarhus (1982), Barcelona (1983), Antwerp (1984), Nafplion (1985), Rennes (1986), Karlsruhe (1987), Tampere (1988), Stresa (1989), Warwick (1990), Madrid (1991), Vienna (1992), Lund (1993), Jerusalem (1994), Szeged (1995), Paderborn (1996), Bo- gna (1997), and Aalborg (1998).In the year 2000 ICALP will be held in Geneva.

This volume contains the proceedings of the 21st International Conference on Application and Theory of Petri Nets. The aim of the Petri net conferences is to createaforumfordiscussingprogressintheapplicationandtheoryofPetrinets. Typically, the conferenceshave 100{150participants{ one third of these coming from industry while the rest are from universities and research institutions. The conferences always take place in the last week of June. The conference and a number of other activities are co-ordinated by a ste- ingcommittee withthe followingmembers:G.Balbo(Italy),J.Billlington(A- tralia),G.De Michelis(Italy),C.Girault(France),K.Jensen(Denmark),S.- magai (Japan), T. Murata (USA), C. A. Petri (Germany; honorary member), W. Reisig (Germany), G. Roucairol (France), G. Rozenberg (The Netherlands; chairman), and M. Silva (Spain). Otheractivitiesbeforeandduringthe2000conferenceincludedtoolpresen- tions and demonstrations, a meeting on \Interchange Formats", extensive int- ductorytutorials,twoadvancedtutorialson\HardwareDesign"and\Timedand Hybrid Automata", and two workshops on \Software Engineering" and \Pr- tical Use of High-Level Nets".The tutorial notes and workshop proceedings are not published in these proceedings, but copies are available from the organisers. The 2000 conference was organised by the CPN Group at the University of Aarhus, Denmark. We would like to thank the organisers (see next page) and their teams. WewouldliketothankverymuchallthosewhosubmittedpaperstothePetri net conference.We receiveda totalof 57submissions from 20di erent countries. This volume comprises the papers that were accepted for presentation. Invited lectures were given by Jordi Cortadella, Philippe Darondeau, Gregor Engels, Serge Haddad, Kim Guldstrand Larsen, and Ole Lehrmann Madsen.

This volume contains papers selected for presentation at the Silver Jubilee 25th Symposium on Mathematical Foundations of Computer Science | MFCS 2000, held in Bratislava, Slovakia, August 28 { September 1, 2000. MFCS 2000 was organized under the auspices of the Minister of Education of the Slovak Republic, Milan Ft a cnik, by the Slovak Society for Computer Science, and the Comenius University in Bratislava, in cooperation with other institu- ons in Slovakia. It was supported by the European Association for Theoretical Computer Science, the European Research Consortium for Informatics and - thematics, and the Slovak Research Consortium for Informatics and Mathe- tics. The series of MFCS symposia, organized alternately in the Czech Republic, Poland, and Slovakia since 1972, has a well-established tradition. The MFCS symposia encourage high-quality research in all branches of theoretical computer science. Their broad scope provides an opportunity of bringing together spec- lists who do not usually meet at specialized conferences.The previous meetings took place in Jablonna, 1972; Strbsk e Pleso, 1973; Jadwisin, 1974; Mari ansk e L azn e, 1975; Gdansk, 1976; Tatransk a Lomnica, 1977; Zakopane, 1978; Olomouc, 1979; Rydzina, 1980; Strbsk e Pleso, 1981; Prague, 1984; Bratislava, 1986; C- lsbad, 1988; Porabk a-Kozubnik, 1989; Bansk a Bystrica, 1990; Kazimierz Dolny, 1991; Prague, 1992; Gdansk, 1993, Ko sice, 1994; Prague, 1995; Krak ow, 1996; Bratislava, 1997; Brno, 1998; and Szklarska Poreba, 1999.

This book constitutes the refereed proceedings of the 35th Conference on Current Trends in Theory and Practice of Computer Science, SOFSEM 2009, held in Špindleruv Mlýn, Czech Republic, in January 2009.The 49 revised full papers, presented together with 9 invited contributions, were carefully reviewed and selected from 132 submissions. SOFSEM 2009 was organized around the following four tracks: Foundations of Computer Science; Theory and Practice of Software Services; Game Theoretic Aspects of E-commerce; and Techniques and Tools for Formal Verification.

This book constitutes the refereed proceedings of the 12th International Conference on Concurrency Theory, CONCUR 2001, held in Aalborg, Denmark in August 2001.The 32 revised full papers presented together with six invited contributions were carefully reviewed and selected from 78 submissions. The papers are organized in topical sections on mobility, probabilistic systems, model checking, process algebra, unfoldings and prefixes, logic and compositionality, and games.

ETAPS 2002 is the ?fth instance of the European Joint Conferences on Theory and Practice of Software. ETAPS is an annual federated conference that was established in 1998by combining a number of existing and new conferences. This year it comprises ?ve conferences (FOSSACS, FASE, ESOP, CC, TACAS), thirteen satellite workshops (ACL2, AGT, CMCS, COCV, DCC, INT, LDTA, SC, SFEDL, SLAP, SPIN, TPTS and VISS), eight invited lectures (not including those that are speci?c to the satellite events), and several tutorials. The events that comprise ETAPS address various aspects of the system - velopment process, including speci?cation, design, implementation, analysis and improvement. The languages, methodologies and tools which support these - tivities are all well within its scope. Di?erent blends of theory and practice are represented, with an inclination towards theory with a practical motivation on one hand and soundly-based practice on the other. Many of the issues involved in software design apply to systems in general, including hardware systems, and the emphasis on software is not intended to be exclusive.

This book constitutes the refereed proceedings of the 12th International Conference on Concurrency Theory, CONCUR 2001, held in Aalborg, Denmark in August 2001.The 32 revised full papers presented together with six invited contributions were carefully reviewed and selected from 78 submissions. The papers are organized in topical sections on mobility, probabilistic systems, model checking, process algebra, unfoldings and prefixes, logic and compositionality, and games.

ETAPS 2002 is the ?fth instance of the European Joint Conferences on Theory and Practice of Software. ETAPS is an annual federated conference that was established in 1998by combining a number of existing and new conferences. This year it comprises ?ve conferences (FOSSACS, FASE, ESOP, CC, TACAS), thirteen satellite workshops (ACL2, AGT, CMCS, COCV, DCC, INT, LDTA, SC, SFEDL, SLAP, SPIN, TPTS and VISS), eight invited lectures (not including those that are speci?c to the satellite events), and several tutorials. The events that comprise ETAPS address various aspects of the system - velopment process, including speci?cation, design, implementation, analysis and improvement. The languages, methodologies and tools which support these - tivities are all well within its scope. Di?erent blends of theory and practice are represented, with an inclination towards theory with a practical motivation on one hand and soundly-based practice on the other. Many of the issues involved in software design apply to systems in general, including hardware systems, and the emphasis on software is not intended to be exclusive.

This volume presents the proceedings of the Sixth International Joint Conference on the Theory and Practice of Software Engineering, TAPSOFT '95, held in Aarhus, Denmark in May 1995. TAPSOFT '95 celebrates the 10th anniversary of this conference series started in Berlin in 1985 to bring together theoretical computer scientists and software engineers (researchers and practitioners) with a view to discussing how formal methods can usefully be applied in software development.The volume contains seven invited papers, among them one by Vaugham Pratt on the recently revealed bug in the Pentium chip, and 44 revised full papers selected from a total of 147 submissions. In addition the TAPSOFT '95 proceedings contains 10 tool descriptions.

This book constitutes the strictly refereed post-workshop proceedings of the 11th International Workshop on Computer Science Logic, CSL '97, held as the 1997 Annual Conference of the European Association on Computer Science Logic, EACSL, in Aarhus, Denmark, in August 1997.The volume presents 26 revised full papers selected after two rounds of refereeing from initially 92 submissions; also included are four invited papers. The book addresses all current aspects of computer science logics and its applications and thus presents the state of the art in the area.

ICALP { the International Colloquium on Automata, Languages, and Progr- ming { is a series of annual conferences of the European Association for Th- retical Computer Science (EATCS). ICALP'99 was organized by the Institute of Computer Science of the Academy of Sciences of the Czech Republic in - operation with the Action M Agency. Stimulated by the positive experience from previous meetings, the guiding idea of the ICALP'99 organization was to keep and to enhance the idea of a parallel two{track conference with invited plenary talks. Similarly to the two parts of the journal Theoretical Computer Science, Track A of the meeting is devoted to Algorithms, Automata, Complexity, and Games, and Track B to Logic, Semantics, and Theory of Programming. The Program Committee was structured along these same lines. As a further inno- tion, ICALP'99 was coordinated with the European Symposium on Algorithms (ESA'99) in such a way that both conferences took place in the same location with the former immediately followed by the latter. ICALP'99 was the 26th in the series of ICALP colloquia. Previous colloquia were held in Paris (1972), Saarbruc .. ken (1974), Edinburgh (1976), Turku (1977), Udine (1978), Graz (1979), Amsterdam (1980), Haifa (1981), Aarhus (1982), Barcelona (1983), Antwerp (1984), Nafplion (1985), Rennes (1986), Karlsruhe (1987), Tampere (1988), Stresa (1989), Warwick (1990), Madrid (1991), Vienna (1992), Lund (1993), Jerusalem (1994), Szeged (1995), Paderborn (1996), Bo- gna (1997), and Aalborg (1998).In the year 2000 ICALP will be held in Geneva.

This volume contains the proceedings of the 21st International Conference on Application and Theory of Petri Nets. The aim of the Petri net conferences is to createaforumfordiscussingprogressintheapplicationandtheoryofPetrinets. Typically, the conferenceshave 100{150participants{ one third of these coming from industry while the rest are from universities and research institutions. The conferences always take place in the last week of June. The conference and a number of other activities are co-ordinated by a ste- ingcommittee withthe followingmembers:G.Balbo(Italy),J.Billlington(A- tralia),G.De Michelis(Italy),C.Girault(France),K.Jensen(Denmark),S.- magai (Japan), T. Murata (USA), C. A. Petri (Germany; honorary member), W. Reisig (Germany), G. Roucairol (France), G. Rozenberg (The Netherlands; chairman), and M. Silva (Spain). Otheractivitiesbeforeandduringthe2000conferenceincludedtoolpresen- tions and demonstrations, a meeting on \Interchange Formats", extensive int- ductorytutorials,twoadvancedtutorialson\HardwareDesign"and\Timedand Hybrid Automata", and two workshops on \Software Engineering" and \Pr- tical Use of High-Level Nets".The tutorial notes and workshop proceedings are not published in these proceedings, but copies are available from the organisers. The 2000 conference was organised by the CPN Group at the University of Aarhus, Denmark. We would like to thank the organisers (see next page) and their teams. WewouldliketothankverymuchallthosewhosubmittedpaperstothePetri net conference.We receiveda totalof 57submissions from 20di erent countries. This volume comprises the papers that were accepted for presentation. Invited lectures were given by Jordi Cortadella, Philippe Darondeau, Gregor Engels, Serge Haddad, Kim Guldstrand Larsen, and Ole Lehrmann Madsen.

This volume contains papers selected for presentation at the Silver Jubilee 25th Symposium on Mathematical Foundations of Computer Science | MFCS 2000, held in Bratislava, Slovakia, August 28 { September 1, 2000. MFCS 2000 was organized under the auspices of the Minister of Education of the Slovak Republic, Milan Ft a cnik, by the Slovak Society for Computer Science, and the Comenius University in Bratislava, in cooperation with other institu- ons in Slovakia. It was supported by the European Association for Theoretical Computer Science, the European Research Consortium for Informatics and - thematics, and the Slovak Research Consortium for Informatics and Mathe- tics. The series of MFCS symposia, organized alternately in the Czech Republic, Poland, and Slovakia since 1972, has a well-established tradition. The MFCS symposia encourage high-quality research in all branches of theoretical computer science. Their broad scope provides an opportunity of bringing together spec- lists who do not usually meet at specialized conferences.The previous meetings took place in Jablonna, 1972; Strbsk e Pleso, 1973; Jadwisin, 1974; Mari ansk e L azn e, 1975; Gdansk, 1976; Tatransk a Lomnica, 1977; Zakopane, 1978; Olomouc, 1979; Rydzina, 1980; Strbsk e Pleso, 1981; Prague, 1984; Bratislava, 1986; C- lsbad, 1988; Porabk a-Kozubnik, 1989; Bansk a Bystrica, 1990; Kazimierz Dolny, 1991; Prague, 1992; Gdansk, 1993, Ko sice, 1994; Prague, 1995; Krak ow, 1996; Bratislava, 1997; Brno, 1998; and Szklarska Poreba, 1999.

This book constitutes the refereed proceedings of the 35th Conference on Current Trends in Theory and Practice of Computer Science, SOFSEM 2009, held in Špindleruv Mlýn, Czech Republic, in January 2009.The 49 revised full papers, presented together with 9 invited contributions, were carefully reviewed and selected from 132 submissions. SOFSEM 2009 was organized around the following four tracks: Foundations of Computer Science; Theory and Practice of Software Services; Game Theoretic Aspects of E-commerce; and Techniques and Tools for Formal Verification.