SAT Solver CNF Constraint Handling for Combinatorial Optimization

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Current methods for solving combinatorial optimization problems using simulated annealing face challenges in efficiently handling constraint terms, leading to increased computation time and reduced accuracy due to the steepness of the solution space, especially when multiple constraints are imposed.

Innovation Solution

A combinatorial optimization problem solution device and method that transforms constraints into Conjunctive Normal Form (CNF) and uses a SAT solver to handle constraints like one-hot and Weighted Sum constraints directly, allowing the solver to find candidate solutions that satisfy all constraints more quickly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If simulated annealing method is used to solve combinatorial optimization problems with multiple constraints, then the method can handle various problem types, but the computation time increases and accuracy decreases due to the steepness of the solution space

Engineering Contradiction:
Improveability to handle various combinatorial optimization problemsVSAvoidcomputation time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent segments the constraint handling into two distinct parts: (1) constraints transformed into CNF form are handled by the SAT solver, and (2) other constraints are handled by the simulated annealing process. This segmentation allows each solver to focus on its strengths, with the SAT solver efficiently handling logical constraints and the SA method optimizing the objective function, thereby reducing overall computation time while maintaining versatility.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary mechanism where constraints are transformed into CNF (Conjunctive Normal Form) and processed by a SAT solver before being fed into the simulated annealing process. This intermediary step acts as a bridge that pre-processes constraints in a form that accelerates the subsequent optimization, reducing the steepness issue and computation time while preserving the ability to handle diverse combinatorial optimization problems.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If simulated annealing method is used to solve combinatorial optimization problems with multiple constraints, then the method can find approximate solutions, but the accuracy decreases due to the steepness of the solution space

Engineering Contradiction:
Improvesolution accuracyVSAvoidcomplexity of constraint handling
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the solution process into two phases: first, the SAT solver efficiently finds assignments that satisfy CNF-transformed constraints, and second, the simulated annealing process optimizes the objective function while respecting remaining constraints. This segmentation improves solution accuracy by ensuring constraints are systematically satisfied before optimization, reducing the steepness problem that plagues pure SA approaches.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent substitutes the purely mechanical simulated annealing constraint satisfaction mechanism with a logical SAT solving approach for CNF constraints. This substitution replaces the trial-and-error nature of SA constraint checking with a more rigorous logical deduction process, thereby improving solution accuracy and reliability while managing complexity through the use of established SAT solving algorithms.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If constraints are transformed into CNF form and handled by SAT solver, then the solution process speeds up, but the device complexity increases

Engineering Contradiction:
Improvesolution process speedVSAvoidcomplexity of solver system
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent merges two established solving approaches—SAT solving and simulated annealing—into a hybrid system that leverages the strengths of both. By combining these solvers, the system achieves accelerated performance through the SAT solver's efficient constraint handling while maintaining the optimization capabilities of simulated annealing, thereby improving productivity without excessively increasing overall system complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent creates a universal solver framework that can handle both CNF constraints (via SAT solver) and general optimization objectives (via simulated annealing) within a single integrated system. This multi-functional approach allows the same system architecture to process diverse constraint types and optimization problems, improving productivity across multiple problem domains while managing complexity through a unified interface.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentUS20250103673A1Combinatorial optimization problem solution device and combinatorial optimization problem solution method
Publication Date: 2025.03.27 NEC CORP
  • US20250103673A1 patent drawing
  • US20250103673A1 patent drawing
  • US20250103673A1 patent drawing

AI summary

By solving SAT expressed in a form of CNF in which constraints other than a no-transformation constraint, which is a constraint that satisfies a prescribed condition among one or more constraints imposed on a combinatorial optimization problem, are transformed, so that the no-transformation constraint is satisfied, a solution unit obtains a combination of values of multiple variables of the combinatorial optimization problem, wherein the combination is a candidate of solution of the combinatorial optimization problem and satisfies the one or more constraints.