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10:15-10:45Coffee Break
10:45-13:05 Session 138E: Modal and Temporal Reasoning
Location: FH, Hörsaal 5
Optimal tableaux-based decision procedure for testing satisfiability in the Alternating-time temporal logic ATL+
SPEAKER: Amélie David

ABSTRACT. We develop a tableaux-based decision method for constructive satisfiability testing and model synthesis in the fragment ATL+ of the full Alternating time temporal logic ATL*. The method extends in an essential way a previous developed tableaux-based decision method for ATL and works in 2EXPTIME, which is the optimal worst case complexity of the satisfiability problem for ATL+. We also discuss how suitable parameterizations and syntactic restrictions on the class of input ATL+ formulae can reduce the complexity of the satisfiability problem.

dTL²: Differential Temporal Dynamic Logic with Nested Modalities for Hybrid Systems
SPEAKER: unknown

ABSTRACT. The differential temporal dynamic logic dTL² is a logic to specify temporal properties of hybrid systems. It combines differential dynamic logic with temporal logic to reason about the intermediate states reached by a hybrid system. The logic dTL² supports some branching and linear time temporal properties of CTL*. We provide a semantics and a proof system for the logic dTL², and show its usefulness for nontrivial temporal properties of hybrid systems. We take particular care to handle the case of alternating universal dynamic and existential temporal modalities and its dual, solving an open problem formulated in previous work.

Axioms vs Hypersequent Rules with Context Restrictions: Theory and Applications

ABSTRACT. We investigate the connections between hypersequent rules with context restrictions and Hilbert axioms extending classical (and intuitionistic) propositional logic. We introduce sufficient syntactic conditions for cut elimination in such hypersequent calculi, translations between rules with context restrictions and axioms (and vice versa), and general decidability and complexity results. Our work subsumes many logic-tailored results, entails finite axiomatisability for a number of normal modal logics given by simple frame properties, and provides a method to construct cut-free hypersequent calculi from a set of axioms. As a case study we obtain a new cut-free hypersequent calculus and complexity bound for the logic of uniform deontic frames.

Clausal Resolution for Modal Logics of Confluence

ABSTRACT. We present a clausal resolution-based method for normal modal logics of confluence, whose Kripke semantics are based on frames characterised by appropriate instances of the Church-Rosser property. Here we restrict attention to eight families of such logics. We show how the inference rules related to the normal logics of confluence can be systematically obtained from the parametrised axioms that characterise such systems. We discuss soundness, completeness, and termination of the method. In particular, completeness can be modularly proved by showing that the conclusions of each newly added inference rule ensures that the corresponding conditions on frames hold. Some examples are given in order to illustrate the use of the method.

Implementing Tableaux Calculi Using BDDs: BDDTab System Description
SPEAKER: unknown

ABSTRACT. Binary Decision Diagrams (BDDs) have been used to decide satisfiability and validity in various non-classical logics by directly implementing the finite property method for these logics. We instead present a method for using Binary Decision Diagrams as an underlying data structure for implementing the tableau method itself. We demonstrate our method by implementing the standard tableau calculi for automated reasoning in propositional modal logics K and S4, along with extensions to the multiple and inverse modalities of ALCI. We evaluate our implementation of such a reasoner using several K and S4 benchmark sets, as well as some ALC and ALCI ontologies. We show, with comparison to FaCT++ and InKreSAT, that it can compete with other state of the art methods of reasoning in propositional modal logic. We also discuss how this technique extends to tableaux for other propositional logics.

13:00-14:30Lunch Break
14:30-16:00 Session 140E: FLoC Inter-Conference topic: SAT/SMT/QBF (joint with CAV)
Location: FH, Hörsaal 5
Approximations for Model Construction
SPEAKER: unknown

ABSTRACT. We consider the problem of efficiently computing models for satisfiable constraints, in the presence of complex background theories such as floating-point arithmetic (FPA). Model construction has various applications, for instance the automatic generation of test inputs. It is well-known that naive encoding of constraints into simpler theories (for instance, bit-vectors or propositional logic) can lead to a drastic increase in size, and be unsatisfactory in terms of memory and runtime needed for model construction. We define a framework for systematic application of approximations in order to speed up model construction. Our method is more general than previous techniques in the sense that approximations that are neither under- nor over-approximations (or the combination of both) can be used, and shows promising results in practice.

A Tool that Incrementally Approximates Finite Satisfiability in Full Interval Temporal Logic
SPEAKER: Martin Lange

ABSTRACT. Interval Temporal Logic (ITL) is a powerful formalism to reason about sequences of events that can occur simultaneously and in an overlapping fashion. Despite its importance for various application domains, little tool support for automated ITL reasoning is available, possibly also owed to ITL's undecidability.

We consider the bounded satisfiability which approximates finite satisfiability and is only NP-complete. We provide an encoding into SAT that makes use of the power of modern incremental SAT solvers and present a tool which tests an ITL specification for finite satisfiability.

StarExec: a Cross-Community Infrastructure for Logic Solving

ABSTRACT. We introduce StarExec, a public web-based service built to facilitate the experimental evaluation of logic solvers, broadly understood as automated tools based on formal reasoning. Examples of such tools include theorem provers, SAT and SMT solvers, constraint solvers, model checkers, and software verifiers. The service, running on a compute cluster with 380 processors and 23 terabytes of disk space, is designed to provide a single piece of storage and computing in- frastructure to logic solving communities and their members. It aims at reducing duplication of effort and resources as well as enabling individual researchers or groups with no access to comparable infrastructure. StarExec allows community organizers to store, manage and make available benchmark libraries; competition organizers to run logic solver competitions; and community members to do com- parative evaluations of logic solvers on public or private benchmark problems.

Skeptik [System Description]
SPEAKER: unknown

ABSTRACT. This paper introduces Skeptik: a system for checking, compressing and improving proofs obtained by sat- and smt-solvers.

16:00-16:50 Session 142: Modal Logic
Location: FH, Hörsaal 5
Terminating Minimal Model Generation Procedures for Propositional Modal Logics
SPEAKER: unknown

ABSTRACT. Model generation and minimal model generation are useful for tasks such as model checking and for debugging of logical specifications. This paper presents terminating procedures for the generation of models minimal modulo subset-simulation for the modal logic K and all combinations of extensions with the axioms T, B, D, 4 and 5. Our procedures are minimal model sound and complete. Compared with other minimal model generation procedures, our procedures benefit from smaller search spaces and fewer models are returned. To make the models most effective for users, our minimal model criterion is designed to be semantically meaningful, intuitive and contain minimal amount of information. Depending on the logic, termination is ensured by a variation of equality blocking.

COOL -- A Generic Satisfiability Checker For Coalgebraic Logics with Global Assumptions (System Description)

ABSTRACT. We describe the Coalgebraic Ontology Logic solver COOL, a generic reasoner that decides the satisfiability of modal formulas (with nominals) with respect to a set of global assumptions --a TBox in Description Logics parlance. The level of generality is that of coalgebraic logic, a logical framework covering a wide range of modal logics, beyond relational semantics. The core of COOL is an efficient unlabelled tableaux search procedure using global caching. Concrete logics are added by implemening the corresponding (one-step) tableaux rules. The logics covered at the moment are (multi-modal) K and KD (i.e., serial relations), graded modal logic and Pauly's Coalition Logic (the next-step fragment of Alternating-time Temporal Logic), plus every logic that arises from the above as a product (modal fusion) or coproduct of the underlying functors, which are handled automatically in a generic way. We compare the performance of COOL with state-of-the-art reasoners.

16:00-16:30Coffee Break
08:45-10:15 Session 144A: VSL Keynote Talk
Location: EI, EI 7 + EI 9, EI 10 + FH, Hörsaal 1
VSL Keynote Talk: Ontology-Based Monitoring of Dynamic Systems
SPEAKER: Franz Baader

ABSTRACT. Our understanding of the notion "dynamic system" is a rather broad one: such a system has states, which can change over time. Ontologies are used to describe the states of the system, possibly in an incomplete way. Monitoring is then concerned with deciding whether some run of the system or all of its runs satisfy a certain property, which can be expressed by a formula of an appropriate temporal logic. We consider different instances of this broad framework, which can roughly be classified into two cases. In one instance, the system is assumed to be a black box, whose inner working is not known, but whose states can be (partially) observed during a run of the system. In the second instance, one has (partial) knowledge about the inner working of the system, which provides information on which runs of the system are possible.

In this talk, we will review some of our recent research that investigates different instances of this general framework of ontology-based monitoring of dynamic systems. We will also sketch possible extensions towards probabilistic reasoning and the integration of mathematical modelling of dynamical systems.

19:00-20:00 Session 149A: VSL Public Lecture 2
Location: MB, Kuppelsaal
VSL Public Lecture: Vienna Circle(s) - Between Philosophy and Science in Cultural Context

ABSTRACT. The Vienna Circle of Logical Empiricism, which was part of the intellectual movement of Central European philosophy of science, is certainly one of the most important currents in the emergence of modern philosophy of science. Apart from this uncontested historical fact there remains the question of the direct and indirect influence, reception and topicality of this scientific community in contemporary philosophy of science in general as well as in the philosophy of the individual sciences, including the formal and social sciences. 

First, I will characterize the road from the Schlick-Circle to contemporary philosophy of science. Second, I will refer to "the present situation in the philosophy of science" by identifying relevant impacts, findings, and unfinished projects since the classical Vienna Circle. Third, I will address some specific European features of this globalized philosophical tradition up to the present, and outline future perspectives after the linguistic, historical and pragmatic turns – looking back to the "received view", or standard view of the Vienna Circle.

16:30-19:00 Session 151A: VSL Joint Award Ceremony 2
Location: MB, Kuppelsaal
FLoC Olympic Games Award Ceremony 2

ABSTRACT. The aim of the FLoC Olympic Games is to start a tradition in the spirit of the ancient Olympic Games, a Panhellenic sport festival held every four years in the sanctuary of Olympia in Greece, this time in the scientific community of computational logic. Every four years, as part of the Federated Logic Conference, the Games will gather together all the challenging disciplines from a variety of computational logic in the form of the solver competitions.

At the Award Ceremonies, the competition organizers will have the opportunity to present their competitions to the public and give away special prizes, the prestigious Kurt Gödel medals, to their successful competitors. This reinforces the main goal of the FLoC Olympic Games, that is, to facilitate the visibility of the competitions associated with the conferences and workshops of the Federated Logic Conference during the Vienna Summer of Logic.

This award ceremony will host the

  • Fifth Answer Set Programming Competition (ASPCOMP 2014);
  • The 7th IJCAR ATP System Competition (CASC-J7);
  • Hardware Model Checking Competition (HWMCC 2014);
  • OWL Reasoner Evaluation (ORE 2014);
  • Satisfiability Modulo Theories solver competition (SMT-COMP 2014);
  • Competition on Software Verification (SV-COMP 2014);
  • Syntax-Guided Synthesis Competition (SyGuS-COMP 2014);
  • Synthesis Competition (SYNTCOMP 2014); and
  • Termination Competition (termCOMP 2014).
Lifetime Achievement Award

ABSTRACT. Werner "Jimmy" DePauli-Schimanovich is being honored for his contributions to Gödel research, for his efforts towards re-establishing Vienna as a center of logic in the second half of the past century, and for extending the outreach of formal logic and logical thinking to other disciplines. The books about Gödel he authored, co-authored, or edited contain precious contributions of historical, philosophical, and mathematical value. His film on Gödel, and related articles and TV testimonials, attracted the general public to Gödel and his work. Moreover, DePauli-Schimanovich has unceasingly and successfully fought to re-establish logic in Vienna. He has inspired and encouraged a large number of students and young researchers, has organised meetings and social gatherings, and has created an intellectual home for scholars of logic. His activities significantly contributed to filling the intellectual vacuum in logic research that had developed in Austria in the years 1938–1945 and well into the post-war period. He was a main initiator and co-founder of the International Kurt Gödel Society. Jimmy’s research in logic involved criticism of current axiomatisations of set theory and development of new systems of naïve set theory. In informatics, DePauli-Schimanovich was co-founder and co-organiser of EuroCAST, a conference series on computer-assisted systems theory meeting alternatively in Vienna and Las Palmas, Gran Canaria. Finally, Jimmy has furthered implementation of logical ideas in disparate fields such as mechanical engineering, automated game playing, urban planning, and by inventing a number of logical games.

Lifetime Achievement Award
SPEAKER: Mingyi Zhang

ABSTRACT. Zhang Mingyi is a pioneer in Artificial Intelligence and Knowledge Representation in China. He has built up a school of non-monotonic logic in Guiyang and has fostered the exchange between Chinese and Western scientists. He has contributed a large number of results on various forms of non-monotonic reasoning, including default logic, answer set programming, and belief revision. In particular, as early as 1992, he has provided important characterizations of various forms of default logic that paved the way for clarifying their computational properties and for developing algorithms for default reasoning.  Jointly with collaborators, he proposed a characterization of answer sets based on sets of generating rules, and introduced the concept of first-order loop formulas to relate answer set programming to classical logic. Other important results relate to theory revision (for example, the proof of the existence and uniqueness of finest splitting of Horn formulae) and to normal forms for Gödel logics. Many of Zhang Mingyi's former students have become internationally respected researchers.

EMCL Distinguished Alumni Award

ABSTRACT. The Free University of Bozen-Bolzano, the Technische Universität Dresden, the Universidade Nova de Lisboa, the Universidad Politécnica de Madrid (until 2010), the Technische Universität Wien, and Australia's Information Communications Technology Research Centre of Excellence (since 2007) are jointly running the European Master's Program in Computational Logic (EMCL) since 2004. The program is supported by the European Union within Erasmus Mundus and Eramsus+. So far, more than 100 students from 39 different countries have successfully completed the distributed master's program with a double or joint degree.

For the first time, the partner institutions are announcing the EMCL Distinguished Alumni Award for outstanding contributions of EMCL graduates to the field of Computational Logic.


FLoC Closing Week 2
SPEAKER: Helmut Veith