Hardware SAT solver based on pipeline execution strategy

Abstract

The invention provides a hardware SAT solver based on a pipeline execution strategy. The hardware SAT solver comprises a preprocessing module, an output module and a clause searching and variable element overturning module. The preprocessing module is used for generating an initial assignment of a CNF formula variable, and extracting unsatisfied clauses under the current assignment and clauses andvariable information of the CNF formula; the output module is used for outputting whether the CNF formula can be met or not; and the clause searching and variable element overturning module is used for synchronously and circularly executing the search of the unsatisfactory clauses by the first thread, the second thread, the third thread and the fourth thread according to a pipeline execution strategy within the preset maximum specified times, overturning clause variable elements according to a certain probability and storing the unsatisfactory clauses after the variable elements are overturned. According to the hardware SAT solver, a pipeline strategy is adopted in the SAT problem solving process, pipeline parallel solving is achieved, the working clock frequency and the throughput rate of a hardware system are increased, and the processing capacity of the solver is enhanced.

Description

technical field [0001] The invention belongs to the technical field of computers, and in particular relates to a SAT solver, in particular to a hardware SAT solver based on a pipeline execution strategy. Background technique [0002] In the SAT problem (satisifiability problem, Boolean satisfiability problem), given a set of finite variable set X={x 1 ,x 2 ,...,x n},x n Can be assigned true (1) or false (0), the literal l i is the variable x i or its negation and have Clause C is formed by text disjunction (meaning "or"), and the conjunction CNF (conjectured normal formula) formula Formed by the conjunction of several clauses, such as That is, a CNF formula consisting of 5 variables and 4 clauses. If any word in a clause is assigned a value of true, then the clause is true or satisfied; if all the words in a clause are assigned a value of false at the same time, it is said that the specified assignment makes the clause false, or the specified assignment makes ...

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Problems solved by technology

Therefore, if the clause is empty, then the clause cannot be satisfied, so the simplified formula is also unsatisfiable

[0006] Most of the existing hardware SAT solvers are executed sequentially. When multiple steps are executed, it often takes multiple clock cycles to wait for the next step after the completion of the previous step. This creates a delay and brings a lot of problems. The clock overhead, the throughput of the system is low

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