Knowledge Tracing with Gaussian Lower Bounds for Explainable Prediction

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Solution Overview

Problem

Existing knowledge tracing systems lack explainability and reliability in real-time predictions, particularly when dealing with limited data, making it difficult for instructors to understand the reasoning behind AI predictions and ensuring the accuracy of these predictions.

Innovation Solution

A knowledge tracing device and method that utilizes a variational parameter determination unit, gradient direction lower bound calculation, and full dimensional lower bound calculation to enhance the explainability and reliability of prediction results by approximating likelihood functions with Gaussian distributions, even in real-time scenarios.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If deep learning methods are used for real-time knowledge tracing, then prediction speed is improved, but explainability of prediction reasons deteriorates

Engineering Contradiction:
Improveprediction speedVSAvoidexplainability of prediction reasons
Core Design Contradiction:
ProductivityVSLoss of information

Solution Approach 1:

The patent segments the knowledge tracing process into distinct components: a prediction unit that performs fast predictions using learned models, and an explanation unit that separately generates human-understandable reasons for predictions. This segmentation allows the system to maintain high prediction speed while providing explainability through dedicated explanation mechanisms rather than relying on opaque deep learning black boxes.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary explanation generation component that translates model predictions into human-understandable formats. This intermediary layer acts as a mediator between the fast prediction engine and the instructor, providing interpretable reasons for predictions without slowing down the core prediction process.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If prediction reliability is improved through more data collection, then prediction accuracy is improved, but real-time responsiveness deteriorates

Engineering Contradiction:
Improveprediction reliabilityVSAvoidreal-time responsiveness
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent performs preliminary actions by pre-processing and pre-training models during offline phases using available data. This allows the system to build robust prediction models in advance, so that during real-time operation, predictions can be made quickly with high reliability without needing to process additional data in real-time.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent dynamically adjusts model parameters and confidence thresholds based on data availability and prediction context. When sufficient data is available, the system can make highly reliable predictions; when data is limited, it adjusts parameters to maintain real-time responsiveness while indicating lower confidence levels.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If complex models are used to provide both explainability and reliability, then prediction quality is improved, but device complexity deteriorates

Engineering Contradiction:
Improveprediction qualityVSAvoidmodel complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the system into specialized modules: prediction modules that handle computational tasks and explanation modules that handle interpretability tasks. This segmentation allows each module to be optimized independently, avoiding the need for a single complex model that attempts to do everything, thereby reducing overall system complexity while maintaining prediction quality.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentUS20260087376A1Knowledge tracing device, method, and program
Publication Date: 2026.03.26 NEC CORP
  • US20260087376A1 patent drawing
  • US20260087376A1 patent drawing
  • US20260087376A1 patent drawing

AI summary

The variational parameter determination unit 81 determines a variational parameter that specifies a position where a likelihood function and a lower bound of the likelihood function to be approximated by Gaussian are in contact. The gradient direction lower bound calculation unit 82 generates a likelihood function made one-dimensional in a gradient direction at the center of a prior distribution and calculates the lower bound of the generated likelihood function. The full dimensional lower bound calculation unit 83 sets covariances in directions other than the gradient direction to an arbitrary covariance and calculates the lower bounds of the set covariances.