Logical Neural Networks for Interpretable Neuro-Symbolic Inference

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Solution Overview

Problem

Current neuro-symbolic reasoning systems face challenges in bridging the gap between formal logic and neural networks, as they are either computationally intensive and require extensive domain expertise or vulnerable to adversarial attacks and uninterpretable black-box nature.

Innovation Solution

A logical neural network (LNN) is developed that merges principled deductive inference via formal logic with data-driven gradient optimized neural network architectures, implementing weighted fuzzy or classical logic to enable interpretable, verifiable, and resilient inference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If formal logic systems are used for deductive inference, then interpretability and verifiability are improved, but computational intensity and requirement for domain expertise increase

Engineering Contradiction:
Improveinterpretability and verifiabilityVSAvoidcomputational intensity and domain expertise requirement
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges formal logic systems with neural network architectures to create a hybrid system that combines the interpretability and verifiability of logic with the computational efficiency and data-driven capabilities of neural networks. The logical neural network integrates symbolic reasoning rules with sub-symbolic learning mechanisms, allowing the system to maintain reliability while reducing computational complexity and domain expertise requirements.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces logical neural networks as an intermediary layer between traditional formal logic systems and standard neural networks. This intermediary structure enables the translation and integration of logical inference rules into neural network computations, facilitating information flow between symbolic and sub-symbolic processing while maintaining both interpretability and computational efficiency.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If traditional neural networks are used for data-driven inference, then computational efficiency and parallel processing are improved, but interpretability and vulnerability to adversarial attacks worsen

Engineering Contradiction:
Improvecomputational efficiency and parallel processingVSAvoidinterpretability and adversarial vulnerability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent combines traditional neural network architectures with formal logic components to create logical neural networks that maintain the computational efficiency and parallel processing capabilities of neural networks while incorporating interpretability mechanisms from formal logic. This merger enables the system to perform efficient computations while producing interpretable results that are less vulnerable to adversarial attacks.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent modifies the parameters and structure of traditional neural networks by integrating logical constraints and symbolic reasoning capabilities. This parameter change transforms the network's behavior to balance computational efficiency with interpretability, making the system more robust against adversarial attacks while maintaining high productivity.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If logical neural networks implement weighted fuzzy logic for continuous differentiability, then adaptability and learning capability are improved, but deviation from classical logical behavior increases

Engineering Contradiction:
Improvecontinuous differentiability and learning capabilityVSAvoidclassical logical behavior accuracy
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements dynamic logical neural networks where the logical operations can adapt between fuzzy and classical modes based on the input data and task requirements. The system dynamically adjusts its reasoning behavior to maintain continuous differentiability for learning while preserving classical logical behavior when needed, achieving both adaptability and reliability through conditional operational modes.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent utilizes parameter changes in the logical neural network to control the degree of fuzziness in logical operations. By adjusting these parameters, the system can transition between fully fuzzy logic (for continuous differentiability and learning) and classical logic (for accurate logical reasoning), thereby balancing adaptability with logical behavior accuracy based on task requirements.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS12045319B2First-order logical neural networks with bidirectional inference
Publication Date: 2024.07.23 INTERNATIONAL BUSINESS MACHINE CORPORATION
  • US12045319B2 patent drawing
  • US12045319B2 patent drawing
  • US12045319B2 patent drawing

AI summary

A system for configuring and using a logical neural network including a graph syntax tree of formulae in a represented knowledgebase connected to each other via nodes representing each proposition. One neuron exists for each logical connective occurring in each formula and, additionally, one neuron for each unique proposition occurring in any formula. All neurons return pairs of values representing upper and lower bounds on truth values of their corresponding subformulae and propositions. Neurons corresponding to logical connectives accept as input the output of neurons corresponding to their operands and have activation functions configured to match the connectives' truth functions. Neurons corresponding to propositions accept as input the output of neurons established as proofs of bounds on the propositions' truth values and have activation functions configured to aggregate the tightest such bounds. Bidirectional inference permits every occurrence of each proposition in each formula to be used as a potential proof.