Ising Model Coefficient Compression for Memory-Constrained Optimization

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Solution Overview

Problem

Current optimization apparatuses face memory limitations when handling large-scale multivariable optimization problems due to the high number of coupling coefficients required for Ising models, which exceed the storage capacity of on-chip memories.

Innovation Solution

The apparatus compresses coupling coefficients based on symmetry or pattern properties of the coefficient matrix, reducing storage needs by storing only the diagonal and symmetric components, and decoding these components as needed for simulated annealing operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If coupling coefficients are stored in internal memory of the optimization apparatus, then access speed is improved, but storage capacity is insufficient for large-scale problems

Engineering Contradiction:
Improveaccess speedVSAvoidstorage capacity
Core Design Contradiction:
SpeedVSQuantity of substance

Solution Approach 1:

The coefficient matrix is segmented into symmetric components and diagonal components, allowing selective storage of only the essential parts. The symmetric components are stored in a compressed format that divides the full matrix into manageable segments, fitting within internal memory capacity while maintaining fast access to all necessary coupling coefficients through computational reconstruction.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention extracts and stores only the diagonal components and symmetric components of the coefficient matrix separately from the full matrix. By taking out and storing only these essential components in a compressed format, the system reduces storage requirements to fit within internal memory while still enabling complete coefficient retrieval for optimization calculations.

Inventive Principle:
Principle #2Taking out (Extraction)

2Measurement precision

If the number of bits for representing coupling coefficients is increased, then precision is improved, but memory storage requirements increase

Engineering Contradiction:
Improvecoefficient precisionVSAvoidmemory storage
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The system stores coupling coefficients with sufficient precision for the optimization task at hand, rather than using maximum possible precision for all coefficients. By applying partial precision where needed and leveraging the compressed storage of symmetric components, the system achieves adequate measurement precision while keeping memory storage requirements within acceptable limits for internal memory.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentUS11748645B2Optimization apparatus and control method thereof
Publication Date: 2023.09.05 FUJITSU LTD
  • US11748645B2 patent drawing
  • US11748645B2 patent drawing
  • US11748645B2 patent drawing

AI summary

An optimization apparatus includes a compression unit, a storage unit, a decoding unit, and an annealing unit. The compression unit outputs compressed coefficient data in which a coefficient matrix including coupling coefficients, each of which indicates a coupling strength between bits of an Ising model obtained by converting a calculation target problem, is compressed on the basis of a symmetry property or a pattern property of the coefficient matrix. The storage unit holds the compressed coefficient data outputted by the compression unit. The decoding unit decodes the compressed coefficient data stored in the storage unit to obtain the coupling coefficients. The annealing unit performs a simulated annealing operation by using the coupling coefficients obtained by the decoding unit.