Mixed Causality Objective Function for Discrete and Continuous Variables

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Solution Overview

Problem

Current causal structure learning models are inadequate for handling mixed datasets containing both continuous and discrete variables, leading to poor performance and precision issues due to high time complexity and loss of information during discretization.

Innovation Solution

A method is introduced that determines a mixed causality objective function using weighted factors to adjust fitting inconsistency, allowing for optimal sparse causal inference across both continuous and discrete variables within a directed acyclic graph framework, thereby improving causality estimation precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If continuous variable discretization is used to process mixed variables in Bayesian network causal model, then the model can handle discrete variables, but information loss occurs and precision decreases

Engineering Contradiction:
Improveability to handle mixed variablesVSAvoidcausality estimation precision
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent segments the causal structure learning process into two distinct phases: equivalence class determination using conditional independence tests, and specific causality determination using fitting inconsistency. This segmentation allows each phase to use methods optimized for its purpose, avoiding the need to discretize continuous variables while still handling mixed variable types effectively.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces fitting inconsistency as an intermediary metric that bridges the gap between equivalence class determination and specific causality determination. This intermediary allows the system to resolve ambiguities in causal directions without losing continuous variable information through discretization.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If data type conversion based on conditional probability distribution is used, then uniform data type handling is achieved, but time complexity increases significantly

Engineering Contradiction:
Improveuniform handling of different data typesVSAvoidcomputational time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent segments the causal learning process into two phases: equivalence class determination (using conditional independence tests) and specific causality determination (using fitting inconsistency). This segmentation avoids the need for comprehensive data type conversions that would be required in a unified approach, thereby reducing computational time.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies partial action by using conditional independence tests only for determining equivalence classes, and then applying fitting inconsistency only for resolving specific causal directions. This partial application of different methods avoids the excessive computational burden of converting all data to a uniform format.

Inventive Principle:
Principle #16Partial or excessive action

3Measurement precision

If conditional independence test is used to determine network structure, then equivalence class can be identified, but specific causality cannot be fully determined

Engineering Contradiction:
Improveequivalence class determination accuracyVSAvoidcausality determination completeness
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent maintains continuity of useful action by seamlessly transitioning from equivalence class determination to specific causality determination. The fitting inconsistency metric continues the causal inference process started by conditional independence tests, resolving ambiguities and completing the causality determination without breaking the analytical chain.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The patent uses feedback by employing fitting inconsistency to evaluate and refine causal hypotheses generated from equivalence class determination. The fitting inconsistency provides feedback on which causal directions are more plausible, allowing the system to iteratively improve its causality estimates.

Inventive Principle:
Principle #23Feedback

4Productivity

If existing sparse causal modeling methods are applied to mixed variables, then high-dimensional causal structure learning is attempted, but precision decreases due to discretization and equivalence class limitations

Engineering Contradiction:
Improvehigh-dimensional causal structure learning capabilityVSAvoidcausality estimation precision
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent segments the causal learning process into two phases: equivalence class determination using conditional independence tests, and specific causality determination using fitting inconsistency. This segmentation allows high-dimensional causal structure learning to proceed without the precision loss associated with discretization, as continuous variables are handled natively throughout the process.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the parameter used for causal inference from discretized counts or converted probability distributions to fitting inconsistency, which is calculated directly from continuous data. This parameter change preserves information and improves precision in high-dimensional mixed variable settings.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS11341424B2Method, apparatus and system for estimating causality among observed variables
Publication Date: 2022.05.24 NEC CORP
  • US11341424B2 patent drawing
  • US11341424B2 patent drawing
  • US11341424B2 patent drawing

AI summary

In response to receiving observed data of mixed observed variables, a mixed causality objective function, being suitable for continuous observed variables and discrete observed variables is determined, wherein the mixed causality objective function includes a causality objective function for continuous observed variables and a causality objective function for discrete observed variables and the fitting inconsistency is adjusted based on weighted factors of the observed variables. Then, the mixed causality objective function is optimally solved by using a mixed sparse causal inference, suitable for both continuous observed variables and discrete observed variables, using the mixed observed data under a constraint of a directed acyclic graph, to estimate causality among the observed variables.