This volume contains the proceedings of the 20th International Conference on AutomatedDeduction (CADE-20).ItwasheldJuly22-27,2005inTallinn,Es- nia,togetherwiththeWorkshoponConstraintsinFormalVeri?cation(CFV'05), the Workshop on Empirically Successful Classical Automated Reasoning (ES- CAR), the Workshop on Non-Theorems, Non-Validity, Non-Provability (DIS- PROVING), and the yearly CADE ATP System Competition (CASC). CADE is the major forum for the presentation of research in all aspects of automated deduction. The ?rst CADE conference was held in 1974. Early CADEs were mostly biennial, and annual conferences started in 1996. Logics of interest include propositional, ?rst-order, equational, higher-order, classical, intuitionistic, constructive, modal, temporal, many-valued, substr- tural, description, and meta-logics, logical frameworks, type theory and set t- ory. Methods of interest include saturation, resolution, tableaux, sequent calculi, term rewriting, induction, uni?cation, constraint solving, decision procedures, model generation,model checking,natural deduction, proofplanning, proof p- sentation, proof checking, and explanation.Applications of interest include hardwareand softwaredevelopment,systems analysisandveri?cation,deductivedatabases,functionalandlogicprogramming, computer mathematics, natural language processing, computational linguistics, robotics, planning, knowledge representation, and other areas of AI. This year, there were 78 submissions, of which 9 system descriptions. Each submissionwasassignedto atleastfour programcommitteemembers,whoca- fully reviewed the papers, in many cases with the help of one or more of a total number of 115 external referees. For each submission at least four reviews were produced and forwarded to the authors. The merits of the submissions were d- cussed by the programcommittee for ten days through the Internet by means of the EasyChair system. Finally, the program committee selected for publication 25 regular research papers and 5 system descriptions.

The refereed proceedings of the 14th International Conference on Rewriting Techniques and Applications, RTA 2003, held in Valencia, Spain in June 2003. The 26 revised regular papers and 6 system descriptions presented together with 3 invited contributions were carefully reviewed and selected from 61 submissions. All current aspects of rewriting are addressed.

This volume contains the papers presented at the Eighth International C- ference on Logic for Programming, Arti?cial Intelligence and Reasoning (LPAR 2001), held on December 3-7, 2001, at the University of Havana (Cuba), together with the Second International Workshop on Implementation of Logics. There were 112 submissions, of which 19 belonged to the special subm- sion category of experimental papers, intended to describe implementations or comparisons of systems, or experiments with systems. Each submission was - viewed by at least three program committee members and an electronic program committee meeting was held via the Internet. The high number of submissions caused a large amount of work, and we are very grateful to the other 31 PC members for their e?ciency and for the quality of their reviews and discussions. Finally, the committee decided to accept 40papers in the theoretical ca- gory, and 9 experimental papers. In addition to the refereed papers, this volume contains an extended abstract of the invited talk by Frank Wolter. Two other invited lectures were given by Matthias Baaz and Manuel Hermenegildo. Apart from the program committee, we would also like to thank the other people who made LPAR 2001 possible: the additional referees; the Local Arran- ` gements Chair Luciano Garc´?a; Andr´es Navarro and Oscar Guell, ¨ who ran the internet-based submission software and the program committee discussion so- ware at the LSI Department lab in Barcelona; and Bill McCune, whose program committee management software was used.

This volume contains the papers presented at the Eighth International C- ference on Logic for Programming, Arti?cial Intelligence and Reasoning (LPAR 2001), held on December 3-7, 2001, at the University of Havana (Cuba), together with the Second International Workshop on Implementation of Logics. There were 112 submissions, of which 19 belonged to the special subm- sion category of experimental papers, intended to describe implementations or comparisons of systems, or experiments with systems. Each submission was - viewed by at least three program committee members and an electronic program committee meeting was held via the Internet. The high number of submissions caused a large amount of work, and we are very grateful to the other 31 PC members for their e?ciency and for the quality of their reviews and discussions. Finally, the committee decided to accept 40papers in the theoretical ca- gory, and 9 experimental papers. In addition to the refereed papers, this volume contains an extended abstract of the invited talk by Frank Wolter. Two other invited lectures were given by Matthias Baaz and Manuel Hermenegildo. Apart from the program committee, we would also like to thank the other people who made LPAR 2001 possible: the additional referees; the Local Arran- ` gements Chair Luciano Garc´?a; Andr´es Navarro and Oscar Guell, ¨ who ran the internet-based submission software and the program committee discussion so- ware at the LSI Department lab in Barcelona; and Bill McCune, whose program committee management software was used.

This volume contains the proceedings of the 20th International Conference on AutomatedDeduction (CADE-20).ItwasheldJuly22-27,2005inTallinn,Es- nia,togetherwiththeWorkshoponConstraintsinFormalVeri?cation(CFV'05), the Workshop on Empirically Successful Classical Automated Reasoning (ES- CAR), the Workshop on Non-Theorems, Non-Validity, Non-Provability (DIS- PROVING), and the yearly CADE ATP System Competition (CASC). CADE is the major forum for the presentation of research in all aspects of automated deduction. The ?rst CADE conference was held in 1974. Early CADEs were mostly biennial, and annual conferences started in 1996. Logics of interest include propositional, ?rst-order, equational, higher-order, classical, intuitionistic, constructive, modal, temporal, many-valued, substr- tural, description, and meta-logics, logical frameworks, type theory and set t- ory. Methods of interest include saturation, resolution, tableaux, sequent calculi, term rewriting, induction, uni?cation, constraint solving, decision procedures, model generation,model checking,natural deduction, proofplanning, proof p- sentation, proof checking, and explanation.Applications of interest include hardwareand softwaredevelopment,systems analysisandveri?cation,deductivedatabases,functionalandlogicprogramming, computer mathematics, natural language processing, computational linguistics, robotics, planning, knowledge representation, and other areas of AI. This year, there were 78 submissions, of which 9 system descriptions. Each submissionwasassignedto atleastfour programcommitteemembers,whoca- fully reviewed the papers, in many cases with the help of one or more of a total number of 115 external referees. For each submission at least four reviews were produced and forwarded to the authors. The merits of the submissions were d- cussed by the programcommittee for ten days through the Internet by means of the EasyChair system. Finally, the program committee selected for publication 25 regular research papers and 5 system descriptions.

The refereed proceedings of the 14th International Conference on Rewriting Techniques and Applications, RTA 2003, held in Valencia, Spain in June 2003. The 26 revised regular papers and 6 system descriptions presented together with 3 invited contributions were carefully reviewed and selected from 61 submissions. All current aspects of rewriting are addressed.

This volume contains the papers presented at the Eighth International C- ference on Logic for Programming, Arti?cial Intelligence and Reasoning (LPAR 2001), held on December 3-7, 2001, at the University of Havana (Cuba), together with the Second International Workshop on Implementation of Logics. There were 112 submissions, of which 19 belonged to the special subm- sion category of experimental papers, intended to describe implementations or comparisons of systems, or experiments with systems. Each submission was - viewed by at least three program committee members and an electronic program committee meeting was held via the Internet. The high number of submissions caused a large amount of work, and we are very grateful to the other 31 PC members for their e?ciency and for the quality of their reviews and discussions. Finally, the committee decided to accept 40papers in the theoretical ca- gory, and 9 experimental papers. In addition to the refereed papers, this volume contains an extended abstract of the invited talk by Frank Wolter. Two other invited lectures were given by Matthias Baaz and Manuel Hermenegildo. Apart from the program committee, we would also like to thank the other people who made LPAR 2001 possible: the additional referees; the Local Arran- ` gements Chair Luciano Garc´?a; Andr´es Navarro and Oscar Guell, ¨ who ran the internet-based submission software and the program committee discussion so- ware at the LSI Department lab in Barcelona; and Bill McCune, whose program committee management software was used.

This volume contains the papers presented at the Eighth International C- ference on Logic for Programming, Arti?cial Intelligence and Reasoning (LPAR 2001), held on December 3-7, 2001, at the University of Havana (Cuba), together with the Second International Workshop on Implementation of Logics. There were 112 submissions, of which 19 belonged to the special subm- sion category of experimental papers, intended to describe implementations or comparisons of systems, or experiments with systems. Each submission was - viewed by at least three program committee members and an electronic program committee meeting was held via the Internet. The high number of submissions caused a large amount of work, and we are very grateful to the other 31 PC members for their e?ciency and for the quality of their reviews and discussions. Finally, the committee decided to accept 40papers in the theoretical ca- gory, and 9 experimental papers. In addition to the refereed papers, this volume contains an extended abstract of the invited talk by Frank Wolter. Two other invited lectures were given by Matthias Baaz and Manuel Hermenegildo. Apart from the program committee, we would also like to thank the other people who made LPAR 2001 possible: the additional referees; the Local Arran- ` gements Chair Luciano Garc´?a; Andr´es Navarro and Oscar Guell, ¨ who ran the internet-based submission software and the program committee discussion so- ware at the LSI Department lab in Barcelona; and Bill McCune, whose program committee management software was used.