# US 12,182,679 B2 · Causality estimation of time series via supervised learning

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- Number: US 12,182,679 B2
- Document ID: US12182679B2
- Status: Granted
- Kind: B2
- Application number: 17/044,783
- Filed: 2019-03-29
- Published: 2021-04-22
- Granted: 2024-12-31
- Earliest claimed: 2018-04-03
- Assignees: Nippon Telegraph and Telephone Corporation
- Applicants: Nippon Telegraph and Telephone Corporation
- Inventors: Yoichi Chikahara; Akinori Fujino
- Web page: https://patentgrep.com/patent/US12182679B2

## CPC

- G06N 20/10: using kernel methods, e.g. support vector machines [SVM]
- G06F 18/214: Generating training patterns; Bootstrap methods, e.g. bagging or boosting
- G06F 18/2431: Multiple classes
- G06N 7/01: Probabilistic graphical models, e.g. probabilistic networks
- G06N 20/00: Machine learning
- G06N: COMPUTING ARRANGEMENTS BASED ON SPECIFIC COMPUTATIONAL MODELS
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

A technique for estimating a causal relation, which can solve problems of a conventional technique and which does not require preliminary setting of a regression model is disclosed. An embodiment of the present invention relates to a causal relation learning device including: a feature value calculation unit that receives a correct label of three or more classification labels related to a causal relation of time-series data and time-series data corresponding to the correct label and calculates a feature value of the time-series data; and a classifier learning unit that learns a classifier using a set of the feature value and the correct label so that an output of the classifier with respect to the feature value is a largest value of an output value of the correct label.

## Claims

### Claim 1

A computer-implemented method for estimating aspects of time-series data, the method comprising:
generating two or more sets of time-series data for machine learning based on a normalized combination of linear time-series data and non-linear time-series data;
receiving a correct label of three or more classification labels for machine learning, wherein the correct label represents a causal relation among the two or more sets of time-series data for machine learning, and the three or more classification labels comprise:
a first set of time-series data is a cause of a second set of time-series data,
the second set of time-series data is a cause of the first set of time-series data, or
no causal relation between the first set of time-series data and the second set of time-series data;
generating a set of feature values of respective sets of the two or more sets of time-series data; and
training, based on a set of the generated feature values and the correct label, a classifier based on machine learning for classifying a causal relation of time series data, wherein a first output value of the classifier using the generated feature value is a maximum output value of the classifier using the correct label; and
estimating, using the trained classifier, the causal relation among a plurality of sets of time-series data.

### Claim 2 (depends on 1)

The computer-implemented method of claim 1, the method further comprising:
when the received two or more sets of time-series data are two sets of time-series data, generating, by the trained classifier, a first set of estimated respective values of the three or more classification labels as output; and
when the received two or more sets of time-series data includes three or more sets of time-series data, generating, by the trained classifier, an average value of a second set of estimated respective values of the three or more classification labels as output.

### Claim 3 (depends on 1)

The computer-implemented method of claim 1, the method further comprising:
receiving a plurality of sets of time-series data for estimating a causal relationship; and
estimating, using the trained classifier, one of the three or more classification labels for the received plurality of sets of time-series data without preconfiguring a regression model for fitting the plurality of sets of time-series data.

### Claim 4 (depends on 1)

The computer-implemented method of claim 1, the method further comprising:
receiving a plurality of sets of time-series data; and
determining, based on the plurality of sets of time-series data using the trained classifier, the correct classification label, wherein the correct classification label is either a set of output of the three or more classification labels or the output with the largest value.

### Claim 5 (depends on 1)

The computer-implemented method of claim 1, wherein the first set of time-series data relates to trend data of foreign currency exchanges, and wherein the second set of the two or more sets of time-series data relates to trend data of stock prices.

### Claim 6

A system for estimating aspects of time-series data, the system comprises:
a processor; and
a memory storing computer-executable instructions that when executed by the processor cause the system to:
generating two or more sets of time-series data for machine learning based on a normalized combination of linear time-series data and non-linear time-series data;
receive a correct label of three or more classification labels for machine learning, wherein the correct label represents a causal relation among the two or more sets of time-series data for machine learning, and the three or more classification labels comprise:
a first set of time-series data is a cause of a second set of time-series data,
the second set of time-series data is a cause of the first set of time-series data, or
no causal relation between the first set of time-series data and the second set of time-series data;
receive the two or more sets of time-series data for machine learning;
generate a set of feature values of respective sets of the two or more sets of time-series data;
train, based on a set of the generated feature values and the correct label, a classifier based on machine learning for classifying a causal relation of time series data, wherein a first output value of the classifier using the generated feature value is a maximum output value of the classifier using the correct label; and
estimate, using the trained classifier, the causal relation among a plurality of sets of time-series data.

### Claim 7 (depends on 6)

The system of claim 6, the computer-executable instructions when executed further causing the system to:
when the received two or more sets of time-series data are two sets of time-series data, generate, by the trained classifier, a first set of estimated respective values of the three or more classification labels as output; and
when the received two or more sets of time-series data includes three or more sets of time-series data, generate, by the trained classifier, average values of a second set of estimated respective values of the three or more classification labels as output.

### Claim 8 (depends on 6)

The system of claim 6, the computer-executable instructions when executed further causing the system to:
receive a plurality of sets of time-series data for estimating a causal relationship; and
estimate, using the trained classifier, one of the three or more classification labels for the received plurality of sets of time-series data without preconfiguring a regression model for fitting the plurality of sets of time-series data.

### Claim 9 (depends on 6)

The system of claim 6, the computer-executable instructions when executed further causing the system to:
receive a plurality of sets of time-series data; and
determine, based on the plurality of sets of time-series data using the trained classifier, the correct classification label, wherein the correct classification label is either a set of output of the three or more classification labels or the output with the largest value.

### Claim 10 (depends on 6)

The system of claim 6, wherein the first set of time-series data relates to trend data of foreign currency exchanges, and wherein the second set of the two or more sets of time-series data relates to trend data of stock prices.

### Claim 11

A computer-readable non-transitory recording medium storing computer-executable instructions that when executed by a processor cause a computer system to:
generating two or more sets of time-series data for machine learning based on a normalized combination of linear time-series data and non-linear time-series data;
receive a correct label of three or more classification labels for machine learning, wherein the correct label represents a causal relation among the two or more sets of time-series data for machine learning, and the three or more classification labels comprise:
a first set of time-series data is a cause of a second set of time-series data,
the second set of time-series data is a cause of the first set of time-series data, or
no causal relation between the first set of time-series data and the second set of time-series data;
receive the two or more sets of time-series data for machine learning;
generate a set of feature values of respective sets of the two or more sets of time-series data;
train, based on a set of the generated feature values and the correct label, a classifier based on machine learning for classifying a causal relation of time series data, wherein a first output value of the classifier using the generated feature value is a maximum output value of the classifier using the correct label; and
estimate, using the trained classifier, the causal relation among a plurality of sets of time-series data.

### Claim 12 (depends on 11)

The computer-readable non-transitory recording medium of claim 11, the computer-executable instructions when executed further causing the system to:
when the received two or more sets of time-series data are two sets of time-series data, generate, by the trained classifier, a first set of estimated respective values of the three or more classification labels as output; and
when the received two or more sets of time-series data includes three or more sets of time-series data, generate, by the trained classifier, average values of a second set of estimated respective values of the three or more classification labels as output.

### Claim 13 (depends on 11)

The computer-readable non-transitory recording medium of claim 11, the computer-executable instructions when executed further causing the system to:
receive a plurality of sets of time-series data for estimating a causal relationship; and
estimate, using the trained classifier, one of the three or more classification labels for the received plurality of sets of time-series data without preconfiguring a regression model for fitting the plurality of sets of time-series data.

### Claim 14 (depends on 11)

The computer-readable non-transitory recording medium of claim 11, the computer-executable instructions when executed further causing the system to:
receive a plurality of sets of time-series data; and
determine, based on the plurality of sets of time-series data using the trained classifier, the correct classification label, wherein the correct classification label is either a set of output of the three or more classification labels or the output with the largest value.

### Claim 15 (depends on 11)

The computer-readable non-transitory recording medium of claim 11, wherein the first set of time-series data relates to trend data of foreign currency exchanges, and wherein the second set of the two or more sets of time-series data relates to trend data of stock prices.
