Abstract: The method of testing for presence of a bug a multithreaded computer program under verification combines the efficiency of testing with the reasoning power of satisfiability modulo theory (SMT) solvers for the verification of multithreaded programs under a user specified test vector. The method performs dynamic executions to obtain both under- and over-approximations of the program, represented as quantifier-free first order logic formulas. The formulas are then analyzed by an SMT solver which implicitly considers all possible thread interleavings. The symbolic analysis may return the following results: (1) it reports a real bug, (2) it proves that the program has no bug under the given input, or (3) it remains inconclusive because the analysis is based on abstractions. In the last case, a refinement procedure is presented that uses symbolic analysis to guide further executions.

Abstract: A beamless mechanic-reversing long stroke pumping unit is provided for petroleum production in diverse types of oil fields. Its mechanic-reversing system consists of differentials, brakes, etc. With two differentials assembled together, taper gears inside them perform revolution and rotation, enabling the pumping unit to achieve direction change and speed change mechanically. The stroke length of the pumping unit can reach 8 meters or longer, and the adjustment process is more convenient than most, by merely tuning the position of the proximity switches. Abrasion of the chains typically caused due to resetting of a motor frequently during operation, is eliminated in this pumping unit. The pumping unit has more reliable operation performance, more convenient maintenance, lower costs, better energy saving effects, and can be applied in land oil fields, offshore oil fields, oil wells with low permeability, etc.

Abstract: A system and method is disclosed for formal verification of software programs that advantageously bounds the ranges of values that a variable in the software can take during runtime.

Abstract: An improved method for automatically improving the precision of an extrapolation operator used, for example, in software program verification in connection with the static analysis and model checking of the software programs which rely on fix-point computation. In particular, a new extrapolation-with-care-set operator, together with a method for gradually increasing the precision of this operation by tightening the care set.

Abstract: A method of obtaining a resolution-based proof of unsatisfiability using a SAT procedure for a hybrid Boolean constraint problem comprising representing constraints as a combination of clauses and interconnected gates. The proof is obtained as a combination of clauses, circuit gates and gate connectivity constraints sufficient for unsatisfiability.

Abstract: A method for bounded model checking of arbitrary Linear Time Logic temporal properties. The method comprises translating properties associated with temporal operators F(p), G(p), U(p, q) and X(p) into property checking schemas comprising Boolean satisfiability checks, wherein F represents an eventuality operator, G represents a globally operator, U represents an until operator and X represents a next-time operator. The overall property is checked in a customized manner by repeated invocations of the property checking schemas for F(p), G(p), U(p, q), X(p) operators and standard handling of atomic propositions and Boolean operators.

Abstract: A symbolic disjunctive image computation method for software models which exploits a number of characteristics unique to software models. More particularly, and according to our inventive method, the entire software model is decomposed into a disjunctive set of submodules and a separate set of transition relations are constructed. An image/reachability analysis is performed wherein an original image computation is divided into a set of image computation steps that may be performed on individual submodules, independently from any others. Advantageously, our inventive method exploits variable locality during the decomposition of the original model into the submodules. By formulating this decomposition as a multi-way hypergraph partition problem, we advantageously produce a small set of submodules while simultaneously minimizing the number of live variable in each individual submodule.

Abstract: A system and method for conducting symbolic partial order reduction for concurrent systems includes determining a guarded independence relation which includes transitions from different threads that are independent for a set of states, when a condition or predicate holds. Partial order reduction is performed using the guarded independence relation to permit automatic pruning of redundant thread interleavings when the guarded independence condition holds.

Abstract: A system and method is disclosed for formal verification of software programs that advantageously translates the software, which can have bounded recursion, into a Boolean representation comprised of basic blocks and which applies SAT-based model checking to the Boolean representation.

Abstract: An improved method for automatically improving the precision of an extrapolation operator used, for example, in software program verification in connection with the static analysis and model checking of the software programs which rely on fix-point computation. In particular, a new extrapolation-with-care-set operator, together with a method for gradually increasing the precision of this operation by tightening the care set.

Abstract: There is provided a method of solving a SAT problem comprising partitioning SAT-formula clauses in the SAT problem into a plurality of partitions. Each of said plurality of partitions is solved as a separate process each, thereby constituting a plurality of processes where each of said process communicates only with a subset of the plurality of processes.

Abstract: A symbolic disjunctive image computation method for software models which exploits a number of characteristics unique to software models. More particularly, and according to our inventive method, the entire software model is decomposed into a disjunctive set of submodules and a separate set of transition relations are constructed. An image/reachability analysis is performed wherein an original image computation is divided into a set of image computation steps that may be performed on individual submodules, independently from any others. Advantageously, our inventive method exploits variable locality during the decomposition of the original model into the submodules. By formulating this decomposition as a multi-way hypergraph partition problem, we advantageously produce a small set of submodules while simultaneously minimizing the number of live variable in each individual submodule.

Abstract: A system and method is disclosed for formal verification of software programs that advantageously bounds the ranges of values that a variable in the software can take during runtime.

Abstract: A system and method is disclosed for formal verification of software programs that advantageously translates the software, which can have bounded recursion, into a Boolean representation comprised of basic blocks and which applies SAT-based model checking to the Boolean representation.

Abstract: A method of obtaining a resolution-based proof of unsatisfiability using a SAT procedure for a hybrid Boolean constraint problem comprising representing constraints as a combination of clauses and interconnected gates. The proof is obtained as a combination of clauses, circuit gates and gate connectivity constraints sufficient for unsatisfiability.

Abstract: There is provided a method of solving a SAT problem comprising partitioning SAT-formula clauses in the SAT problem into a plurality of partitions. Each of said plurality of partitions is solved as a separate process each, thereby constituting a plurality of processes where each of said process communicates only with a subset of the plurality of processes.

Abstract: A method of performing image or pre-image computation for a system is disclosed. The method comprises representing the system by a finite state model; representing state sets using Binary Decision Diagrams (BDDs); performing a satisfiabilty checking (SAT) based backtrack search algorithm, wherein, the SAT decomposes the search over an entire solution space into multiple sub-problems, and wherein a BDD-based image computation is used to solve each sub-problem by enumerating multiple solutions from the solution space. Further, a method for pruning a search space in a SAT procedure is disclosed. The method comprises using BDD Bounding against an implicit disjunction or conjunction of a given set of BDDs; continuing search if a partial assignment of variables satisfies the implicit disjunction or conjunction, and backtracking if a partial assignment of variables does not satisfy the implicit disjunction or conjunction.

Abstract: A method for bounded model checking of arbitrary Linear Time Logic temporal properties. The method comprises translating properties associated with temporal operators F(p), G(p), U(p, q) and X(p) into property checking schemas comprising Boolean satisfiability checks, wherein F represents an eventuality operator, G represents a globally operator, U represents an until operator and X represents a next-time operator. The overall property is checked in a customized manner by repeated invocations of the property checking schemas for F(p), G(p), U(p, q), X(p) operators and standard handling of atomic propositions and Boolean operators.

Abstract: A method for Boolean Satisfiability (SAT). The method comprises using a variable decision heuristic in a SAT algorithm and pruning the search space of SAT using said decision heuristic. The decision heuristic is based on partitioning a conjunctive normal form (CNF) of a Boolean formula corresponding to the SAT and the partitioning is induced by a separator set. An image computaion method that uses the disclosed method for solving the SAT.

Abstract: This disclosure teaches a method of Boolean satisfiability checking (SAT) for a circuit. The method comprises identifying inactive clauses in the conjunctive normal form (CNF) of the circuit and removing the inactive clauses from the CNF.