4 results about "Conjunctive normal form" patented technology

The invention relates to the field of computer science and technology and artificial intelligence, and particularly discloses a MaxSAT initial assignment method based on an improved Johnson algorithm. The maximum satisfiability problem (MaxSAT) is an optimized version of the Boolean satisfiability problem (SAT). The invention provides a new heuristic initial assignment generation method aiming at the problem of low search efficiency caused by the adoption of a complete random initialization strategy by an existing local search solver. The method is realized through the following technical scheme: firstly, inputting a conjunctive normal form of a MaxSAT problem, calculating positive and negative character scores of each variable based on a Johnson algorithm principle, and further obtaining probability estimation that each variable is assigned to be true; then, a threshold value is set to carry out deterministic assignment on the high-confidence-coefficient variable, and an assignment result is propagated in time to simplify a problem structure; iteratively executing calculation, assignment and propagation processes until a preset cycle cut-off condition is reached; and finally, performing probabilistic complementation on the residual variables to generate a complete initial assignment.

The application discloses a conjunctive normal form based semi-tensor product SAT solving method, which comprises the following steps: analyzing conjunctive normal form clauses; according to the analyzed conjunctive normal form clauses, combining each clause C x into a corresponding logical matrix representation M x , and obtaining M x ; combining the obtained M x into a group of matrix expressions through logical relationship; calculating the logical matrix representation according to the semi-tensor product SAT solving; and according to the satisfiable assignment of each C x , taking the intersection of each group of satisfiable assignments to obtain a group of satisfiable Boolean assignments satisfying all independent clauses C. The conjunctive normal form based semi-tensor product SAT solving method and device can reduce the calculation time, improve the calculation efficiency and improve the compactness of the satisfiable solution.

The application discloses a simplification method of a conjunctive normal form probability constraint, and comprises the following steps: given a conjunctive normal form probability constraint, extracting all disjunction clauses in the conjunctive normal form expression in the SQL predicate of the probability constraint; setting the parameters in the relational expression in each disjunction clause, setting as many disjunction clauses as possible to be true, and reducing effective disjunction clauses; further, setting the parameters in the relational expression in the remaining disjunction clauses, and reducing effective relational expressions; finally, simplifying the original expression into a relational expression, a disjunction of multiple non-equivalent relational expressions, or a conjunction of multiple equivalent relational expressions; and finally obtaining the simplified probability constraint.

The application discloses a kind of planning methods for chip wiring layout fusion evolution and SAT solution, it is related to chip design technical field. Including: obtaining the conjunctive normal form of chip wiring layout problem, the coding rule of individual is defined;According to the search strategy and simplified evolution process of stage, search the optimal parameter combination about the value of evolution algorithm super parameter;Based on the optimal parameter combination and individual coding rule, initialize population and carry out iterative evolution;In the iteration process, based on conflict information and optimization target contribution, implement different cross mutation strategy, dynamically adjust the cross rate and mutation rate of each variable, while collecting key information, the individual that does not satisfy constraint is repaired directionally;Finally, according to the evaluation result screening individual, obtain global optimal solution set, realize the efficient solution to chip wiring layout problem, solve the problems such as poor timeliness, weak constraint satisfaction ability and low convergence quality of prior art.