Call for Papers 8th Workshop on Horn Clauses for Verification and Synthesis (HCVS) Co-located with ETAPS 2021 28 March 2021 - Luxembourg, Luxembourg https://www.sci.unich.it/hcvs21/ Invited speakers: Please visit webpage for updates Submission deadlines: - Paper submission: Feb 19, 2021 (extended from 28 Jan 2021) - Paper notification: Mar 15, 2021 - Workshop: Mar 28, 2021 Many Program Verification and Synthesis problems of interest can be modeled directly using Horn clauses and many recent advances in the CLP and CAV communities have centered around efficiently solving problems presented as Horn clauses. This series of workshops aims to bring together researchers working in the two communities of Constraint/Logic Programming (e.g., ICLP and CP), Program Verification (e.g., CAV, TACAS, and VMCAI), and Automated Deduction (e.g., CADE, IJCAR), on the topic of Horn clause based analysis, verification, and synthesis. Horn clauses for verification and synthesis have been advocated by these communities in different times and from different perspectives and HCVS is organized to stimulate interaction and a fruitful exchange and integration of experiences. The workshop follows seven previous meetings: HCVS 2020 in Dublin, Ireland (ETAPS 2020), HCVS 2019 in Prague, Czech Republic (ETAPS 2019), HCVS 2018 in Oxford, UK (CAV, ICLP and IJCAR at FLoC 2018), HCVS 2017 in Gothenburg, Sweden (CADE), HCVS 2016 in Eindhoven, The Netherlands (ETAPS), HCVS 2015 in San Francisco, CA, USA (CAV), and HCVS 2014 in Vienna, Austria (VSL). Topics of interest include, but are not limited to the use of Horn clauses, constraints, and related formalisms in the following areas: -Analysis and verification of programs and systems of various kinds (e.g., imperative, object-oriented, functional, logic, higher-order, concurrent, transition systems, petri-nets, smart contracts) -Program synthesis -Program testing -Program transformation -Constraint solving -Type systems -Machine learning and automated reasoning -CHC encoding of analysis and verification problems -Resource analysis -Case studies and tools -Challenging problems We solicit regular papers describing theory and implementation of Horn-clause based analysis and tool descriptions. We also solicit extended abstracts describing work-in-progress, as well as presentations covering previously published results and posters that are of interest to the workshop. CHC Competition: HCVS 2021 will host the 4th competition on constraint Horn clauses ( CHC-COMP), which will compare state-of-the-art tools for CHC solving for performance and effectiveness on a set of publicly available benchmarks. A report on the 4th CHC-COMP will be part of the workshop's proceedings. The report also contains tool descriptions of the participating solvers. Program Committee: Please visit webpage for updates Submission has to be done in one of the following formats: -Regular papers (up to 12 pages plus bibliography in EPTCS (http://www.eptcs.org/) format), which should present previously unpublished work (completed or in progress), including descriptions of research, tools, and applications. -Tool papers (up to 4 pages in EPTCS format), including the papers written by the CHC-COMP participants, which can outline the theoretical framework, the architecture, the usage, and experiments of the tool. -Extended abstracts (up to 3 pages in EPTCS format), which describe work in progress or aim to initiate discussions. -Presentation-only papers, i.e., papers already submitted or presented at a conference or another workshop. Such papers can be submitted in any format, and will not be included in the workshop post-proceedings. -Posters that are of interest to the workshop All submitted papers will be refereed by the program committee and will be selected for inclusion in accordance with the referee reports. Accepted regular papers and extended abstracts will be published electronically as a volume in the Electronic Proceedings in Theoretical Computer Science (EPTCS) series, see http://www.eptcs.org/ (provided that enough regular papers are accepted). Papers must be submitted through the EasyChair system using the web page: https://easychair.org/conferences/?conf=hcvs2021