https://hal-lirmm.ccsd.cnrs.fr/lirmm-01487646Itsykson, DmitryDmitryItsyksonPDMI RAS - St. Petersburg Department of V.A. Steklov Mathematical Institute - SMI - Steklov Mathematical Institute [Moscow] - RAS - Russian Academy of Sciences [Moscow]Knop, AlexanderAlexanderKnopPDMI RAS - St. Petersburg Department of V.A. Steklov Mathematical Institute - SMI - Steklov Mathematical Institute [Moscow] - RAS - Russian Academy of Sciences [Moscow]Romashchenko, AndreiAndreiRomashchenkoESCAPE - Systèmes complexes, automates et pavages - LIRMM - Laboratoire d'Informatique de Robotique et de Microélectronique de Montpellier - UM - Université de Montpellier - CNRS - Centre National de la Recherche ScientifiqueSokolov, DmitryDmitrySokolovPDMI RAS - St. Petersburg Department of V.A. Steklov Mathematical Institute - SMI - Steklov Mathematical Institute [Moscow] - RAS - Russian Academy of Sciences [Moscow]On OBDD-Based Algorithms and Proof Systems That Dynamically Change Order of VariablesHAL CCSD2017Proof complexityOBDDerror-correcting codesTseitin formulasexpanders[INFO.INFO-CC] Computer Science [cs]/Computational Complexity [cs.CC][INFO.INFO-DM] Computer Science [cs]/Discrete Mathematics [cs.DM]Romashchenko, AndreiFondements du numérique - Dépasser les frontières de l'aléatoire et du calculable - - RaCAF2015 - ANR-15-CE40-0016 - AAPG2015 - VALID - 2019-06-28 15:46:392022-08-05 15:02:592019-06-28 16:03:36enConference papershttps://hal-lirmm.ccsd.cnrs.fr/lirmm-01487646/document10.4230/LIPIcs.STACS.2017.43application/pdf1In 2004 Atserias, Kolaitis and Vardi proposed OBDD-based propositional proof systems that prove unsatisfiability of a CNF formula by deduction of identically false OBDD from OBDDs representing clauses of the initial formula. All OBDDs in such proofs have the same order of variables. We initiate the study of OBDD based proof systems that additionally contain a rule that allows to change the order in OBDDs. At first we consider a proof system OBDD(and, reordering) that uses the conjunction (join) rule and the rule that allows to change the order. We exponentially separate this proof system from OBDD(and)-proof system that uses only the conjunction rule. We prove two exponential lower bounds on the size of OBDD(and, reordering)-refutations of Tseitin formulas and the pigeonhole principle. The first lower bound was previously unknown even for OBDD(and)-proofs and the second one extends the result of Tveretina et al. from OBDD(and) to OBDD(and, reordering). In 2004 Pan and Vardi proposed an approach to the propositional satisfiability problem based on OBDDs and symbolic quantifier elimination (we denote algorithms based on this approach as OBDD(and, exists)-algorithms. We notice that there exists an OBDD(and, exists)-algorithm that solves satisfiable and unsatisfiable Tseitin formulas in polynomial time. In contrast, we show that there exist formulas representing systems of linear equations over F_2 that are hard for OBDD(and, exists, reordering)-algorithms. Our hard instances are satisfiable formulas representing systems of linear equations over F_2 that correspond to some checksum matrices of error correcting codes.