# US 8,572,146 B2 · Comparing data samples represented by characteristic functions

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- Number: US 8,572,146 B2
- Document ID: US8572146B2
- Status: Granted
- Kind: B2
- Application number: 12/857,690
- Filed: 2010-08-17
- Published: 2012-02-23
- Granted: 2013-10-29
- Earliest claimed: 2010-08-17
- Assignees: Fujitsu Limited
- Applicants: Stergios Stergiou; Jawahar Jain
- Inventors: Stergios Stergiou; Jawahar Jain
- Web page: https://patentgrep.com/patent/US8572146B2

## CPC

- H04L 9/3239: {involving non-keyed hash functions, e.g. modification detection codes [MDCs], MD5, SHA or RIPEMD}
- A61B 5/021: Measuring pressure in heart or blood vessels
- A61B 5/02416: {using photoplethysmograph signals, e.g. generated by infrared radiation (A61B5/14552 takes precedence)}
- A61B 5/1455: using optical sensors, e.g. spectral photometrical oximeters
- H04L 2209/805: Lightweight hardware, e.g. radio-frequency identification [RFID] or sensor
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

According to certain embodiments, a first characteristic function representing a first set of samples and a second characteristic function representing a second set of samples are generated. The first characteristic function and the second characteristic function are transformed to a first arithmetic function and a second arithmetic function, respectively. A first hash code and a second hash code are calculated from the first arithmetic function and the second arithmetic function, respectively. If the first hash code equals the second hash code, the first set of samples and the second set of samples are designated as equivalent; otherwise, the first set of samples and the second set of samples are designated as not equivalent.

## Claims

### Claim 1

A method by one or more processors associated with one or more computing devices, one or more of the processors including a memory, the method comprising:
generating, by one or more of the processors, a first characteristic function representing a first set of samples and a second characteristic function representing a second set of samples;
transforming, by one or more of the processors, the first characteristic function and the second characteristic function to a first arithmetic function and a second arithmetic function, respectively;
calculating, by one or more of the processors, a first hash code and a second hash code from the first arithmetic function and the second arithmetic function, respectively;
if the first hash code equals the second hash code, designating, by one or more of the processors, the first set of samples and the second set of samples as equivalent; and
otherwise, designating, by one or more of the processors, the first set of samples and the second set of samples as not equivalent.

### Claim 2 (depends on 1)

The method of claim 1, the generating the first characteristic function further comprising:
representing each sample of the first set of samples as a minterm to yield a first set of minterms; and
generating the first characteristic function from the first set of minterms, the first characteristic function indicating whether a given minterm is a member of the first set of minterms.

### Claim 3 (depends on 2)

The method of claim 2, the representing each sample further comprising:
receiving the each sample, the each sample comprising one or more sensor values; and
for each sensor value, expressing the each sensor value as a binary number using one or more variables allocated to the each sensor value to yield one or more binary numbers.

### Claim 4 (depends on 2)

The method of claim 2, the generating the first characteristic function from the first set of minterms further comprising:
applying a logical OR operation to the minterms of the first set of minterms to generate the first characteristic function.

### Claim 5 (depends on 1)

The method of claim 1, the calculating the first hash code further comprising:
calculating a third hash code of a third characteristic function;
calculating a fourth hash code of a fourth characteristic function, the first characteristic function comprising a Boolean combination of the third characteristic function and the fourth characteristic function; and
calculating the first hash code from an arithmetic combination of the third hash code and the fourth hash code.

### Claim 6 (depends on 1)

The method of claim 1, each sample of the first sample set comprising a tuple of one or more sensor values, each sensor value recording one or more measurements taken by one or more sensors at a parameter value of a parameter.

### Claim 7 (depends on 6)

The method of claim 6, the parameter representing a time, a temperature, or a location.

### Claim 8 (depends on 1)

The method of claim 1, wherein the first and second characteristic functions are represented by a first binary decision diagram (BDD) and second BDD, respectively.

### Claim 9 (depends on 8)

The method of claim 8, wherein the first and second BDD each comprises one or more rooted directed acyclic graphs representing the first and second characteristic functions, respectively.

### Claim 10 (depends on 9)

The method of claim 9, wherein the first and second BDD each comprise a plurality of nodes and a plurality of edges connecting the nodes thereby forming a plurality of paths, each path in the BDD representing a set of variable assignments setting the represented characteristic function to either 1 or 0.

### Claim 11

An apparatus comprising: a memory configured to store a first set of samples and a second set of samples; and one or more processors configured to:
generate a first characteristic function representing the first set of samples and a second characteristic function representing the second set of samples;
transform the first characteristic function and the second characteristic function to a first arithmetic function and a second arithmetic function, respectively;
calculate a first hash code and a second hash code from the first arithmetic function and the second arithmetic function, respectively;
if the first hash code equals the second hash code, designate the first set of samples and the second set of samples as equivalent; and
otherwise, designate the first set of samples and the second set of samples as not equivalent.

### Claim 12 (depends on 11)

The apparatus of claim 11, the generating the first characteristic function further comprising:
representing each sample of the first set of samples as a minterm to yield a first set of minterms; and
generating the first characteristic function from the first set of minterms, the first characteristic function indicating whether a given minterm is a member of the first set of minterms.

### Claim 13 (depends on 12)

The apparatus of claim 12, the representing each sample further comprising:
receiving the each sample, the each sample comprising one or more sensor values; and
for each sensor value, expressing the each sensor value as a binary number using one or more variables allocated to the each sensor value to yield one or more binary numbers.

### Claim 14 (depends on 12)

The apparatus of claim 12, the generating the first characteristic function from the first set of minterms further comprising:
applying a logical OR operation to the minterms of the first set of minterms to generate the first characteristic function.

### Claim 15 (depends on 11)

The apparatus of claim 11, the calculating the first hash code further comprising:
calculating a third hash code of a third characteristic function;
calculating a fourth hash code of a fourth characteristic function, the first characteristic function comprising a Boolean combination of the third characteristic function and the fourth characteristic function; and
calculating the first hash code from an arithmetic combination of the third hash code and the fourth hash code.

### Claim 16 (depends on 11)

The apparatus of claim 11, each sample of the first sample set comprising a tuple of one or more sensor values, each sensor value recording one or more measurements taken by one or more sensors at a parameter value of a parameter.

### Claim 17 (depends on 16)

The apparatus of claim 16, the parameter representing a time, a temperature, or a location.

### Claim 18

One or more non-transitory computer-readable media storing code, when executed by one or more processors, configured to:
generate a first characteristic function representing a first set of samples and a second characteristic function representing a second set of samples;
transform the first characteristic function and the second characteristic function to a first arithmetic function and a second arithmetic function, respectively;
calculate a first hash code and a second hash code from the first arithmetic function and the second arithmetic function, respectively;
if the first hash code equals the second hash code, designate the first set of samples and the second set of samples as equivalent; and
otherwise, designate the first set of samples and the second set of samples as not equivalent.

### Claim 19 (depends on 18)

The media of claim 18, the generating the first characteristic function further comprising:
representing each sample of the first set of samples as a minterm to yield a first set of minterms; and
generating the first characteristic function from the first set of minterms, the first characteristic function indicating whether a given minterm is a member of the first set of minterms.

### Claim 20 (depends on 19)

The media of claim 19, the representing each sample further comprising:
receiving the each sample, the each sample comprising one or more sensor values; and
for each sensor value, expressing the each sensor value as a binary number using one or more variables allocated to the each sensor value to yield one or more binary numbers.

### Claim 21 (depends on 19)

The media of claim 19, the generating the first characteristic function from the first set of minterms further comprising:
applying a logical OR operation to the minterms of the first set of minterms to generate the first characteristic function.

### Claim 22 (depends on 18)

The media of claim 18, the calculating the first hash code further comprising:
calculating a third hash code of a third characteristic function;
calculating a fourth hash code of a fourth characteristic function, the first characteristic function comprising a Boolean combination of the third characteristic function and the fourth characteristic function; and
calculating the first hash code from an arithmetic combination of the third hash code and the fourth hash code.

### Claim 23 (depends on 18)

The media of claim 18, each sample of the first sample set comprising a tuple of one or more sensor values, each sensor value recording one or more measurements taken by one or more sensors at a parameter value of a parameter.

### Claim 24 (depends on 23)

The media of claim 23, the parameter representing a time, a temperature, or a location.