CN112347425A - Method and system for dense subgraph detection based on time sequence - Google Patents

Method and system for dense subgraph detection based on time sequence Download PDF

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CN112347425A
CN112347425A CN202110026174.5A CN202110026174A CN112347425A CN 112347425 A CN112347425 A CN 112347425A CN 202110026174 A CN202110026174 A CN 202110026174A CN 112347425 A CN112347425 A CN 112347425A
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赵禹闳
王巍
施亮
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TONGDUN TECHNOLOGY Co.,Ltd.
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Abstract

The application relates to a method and a system for dense subgraph detection based on time series, wherein the method for dense subgraph detection based on time series comprises the following steps: constructing a three-dimensional transaction matrix, a time set and a user set; then, calculating according to the three-dimensional transaction matrix to obtain a time-dimension transaction sum matrix and a user-dimension transaction sum matrix, and summing the transaction sums to obtain a first sum value; then averaging the first summation value through a time set and a user set to obtain an initial dense subgraph abnormal value; and finally, iteratively calculating and updating the abnormal value of the intensive subgraph by a greedy algorithm, recording the obtained maximum abnormal value of the intensive subgraph, and outputting a time set and a user set corresponding to the maximum abnormal value of the intensive subgraph as detection results. The method solves the problems of low accuracy and long calculation time consumption of fund transaction abnormal dense subgraph detection in the prior art, and improves the abnormal detection precision and the calculation speed.

Description

Method and system for dense subgraph detection based on time sequence
Technical Field
The present application relates to the field of computers, and more particularly, to a method and system for dense subgraph detection based on time series.
Background
With the rapid development of information technology, people increasingly use electronic banks to perform fund operation conveniently and rapidly, however, various phishing, telephone fraud, short message fraud and the like are generated, these various forms of fund fraud behaviors are becoming more and more serious, and based on these problems, the behavior of how to detect abnormal fund transaction of users such as banks, finance and the like has been more and more aroused by people.
In the related art, the fund transaction anomaly detection algorithms are all based on users and commodities and anomaly consideration between the users, such as algorithms like Fraudar, Dspot and FlowScope, and the algorithms cannot detect and obtain feedback results of fund anomaly transactions in real time, and the problems of large calculation amount and long time consumption exist.
At present, no effective solution is provided for the problems of low accuracy rate of abnormal and dense subgraph detection of fund transactions and long time consumption of calculation in the related technology.
Disclosure of Invention
The embodiment of the application provides a time-series-based dense subgraph detection method and a time-series-based dense subgraph detection system, which at least solve the problems of low accuracy and long calculation time consumption of abnormal fund transaction dense subgraph detection in the related technology.
In a first aspect, an embodiment of the present application provides a method for dense subgraph detection based on a time series, where the method includes:
constructing a three-dimensional transaction matrix, a time set and a user set, wherein the dimensionality of the three-dimensional transaction matrix comprises the following steps: transaction time and user, the elements of the three-dimensional transaction matrix comprising: a transaction amount;
calculating to obtain a time-dimension transaction sum matrix and a user-dimension transaction sum matrix according to the three-dimensional transaction matrix, and summing the transaction sums in the elements to obtain a first sum value;
averaging the first summation value through the time set and the user set to obtain an initial dense subgraph abnormal value;
and iteratively calculating and updating the dense subgraph abnormal value through a greedy algorithm, recording the obtained maximum dense subgraph abnormal value, and outputting a time set and a user set corresponding to the maximum dense subgraph abnormal value as detection results.
In some of these embodiments, the summing of the transaction amounts in the elements results in a first summed value
Figure 205611DEST_PATH_IMAGE001
Figure 993438DEST_PATH_IMAGE002
Wherein the content of the first and second substances,
Figure 629956DEST_PATH_IMAGE003
is a set of transaction times that are,
Figure 845037DEST_PATH_IMAGE004
is a set of users who transfer money,
Figure 934216DEST_PATH_IMAGE005
is a collection of users that are to be paid,
Figure 791313DEST_PATH_IMAGE006
is a three-dimensional matrix of transactions and,
Figure 220020DEST_PATH_IMAGE007
is the empirical anomaly score.
In some of these embodiments, the empirical anomaly score comprises:
the experience anomaly score is related to the transaction time and the user, wherein the transaction is anomalous within a preset time, the experience anomaly score is greater than 0, and when the user is a white list user, the experience anomaly score is less than 0.
Therein is provided withIn some embodiments, the averaging of the first summation values by the time set and the user set results in an initial dense subgraph outlier
Figure 668319DEST_PATH_IMAGE008
Figure 448057DEST_PATH_IMAGE009
Wherein the content of the first and second substances,
Figure 640003DEST_PATH_IMAGE003
is a set of transaction times that are,
Figure 188796DEST_PATH_IMAGE004
is a set of users who transfer money,
Figure 11259DEST_PATH_IMAGE005
is a collection of users that are to be paid,
Figure 75030DEST_PATH_IMAGE001
is the first summation value.
In some embodiments, the iteratively calculating and updating the dense subgraph outliers by a greedy algorithm comprises:
acquiring a minimum element in the time-dimension transaction sum matrix and the user-dimension transaction sum matrix to obtain a minimum value;
screening out the corresponding elements of the minimum elements in the time set or the user set to obtain a new time set or a new user set;
calculating to obtain a second summation value through the minimum value, and averaging the second summation value through the new time set and the user set to obtain an updated dense subgraph abnormal value;
and recalculating the three-dimensional transaction matrix, and recalculating the new time-dimension transaction sum matrix and the user-dimension transaction sum matrix through the new three-dimensional transaction matrix.
In some of these embodiments, after recalculating the transaction sum matrix for the new time dimension and the transaction sum matrix for the user dimension, the method includes:
judging whether an empty set exists in the transaction sum matrix of the new time dimension and the transaction sum matrix of the user dimension;
in the case where there is an empty set, the iterative computation terminates.
In some embodiments, after obtaining the transaction amount sum matrix in the time dimension and the transaction amount sum matrix in the user dimension, the method includes:
and constructing an N-branch tree of the transaction sum matrix of the time dimension and the transaction sum matrix of the user dimension.
In a second aspect, an embodiment of the present application provides a system for dense subgraph detection based on time series, where the system includes:
the construction module is used for constructing a three-dimensional transaction matrix, a time set and a user set, wherein the dimensionality of the three-dimensional transaction matrix comprises the following steps: transaction time and user, the elements of the three-dimensional transaction matrix comprising: a transaction amount;
a calculation module for calculating a time dimension transaction sum matrix and a user dimension transaction sum matrix according to the three-dimensional transaction matrix, and summing the transaction amounts in the elements to obtain a first sum value,
averaging the first summation value through the time set and the user set to obtain an initial dense subgraph abnormal value;
and the output module is used for iteratively calculating and updating the dense subgraph abnormal value through a greedy algorithm, recording the obtained maximum dense subgraph abnormal value, and outputting a time set and a user set corresponding to the maximum dense subgraph abnormal value as detection results.
In a third aspect, an embodiment of the present application provides an electronic apparatus, including a memory and a processor, where the memory stores a computer program, and the processor is configured to execute the computer program to perform any one of the methods for dense subgraph detection based on time series.
In a fourth aspect, the present application provides a storage medium, where a computer program is stored, where the computer program is configured to execute any one of the methods for dense subgraph detection based on time series described above when running.
Compared with the related technology, the dense subgraph detection method based on the time series provided by the embodiment of the application constructs a three-dimensional transaction matrix, a time set and a user set based on transaction data, wherein the dimensionality of the three-dimensional transaction matrix comprises the following steps: transaction time and user, elements of the three-dimensional transaction matrix include: a transaction amount; then, calculating according to the three-dimensional transaction matrix to obtain a time-dimension transaction sum matrix and a user-dimension transaction sum matrix, and summing the transaction sums in the elements to obtain a first sum value; then averaging the first summation value through a time set and a user set to obtain an initial dense subgraph abnormal value; and finally, iteratively calculating and updating the abnormal value of the intensive subgraph by a greedy algorithm, recording the obtained maximum abnormal value of the intensive subgraph, and outputting a time set and a user set corresponding to the maximum abnormal value of the intensive subgraph as a detection result, so that the problems of low detection accuracy and long calculation time consumption of the abnormal intensive subgraph in the fund transaction in the prior art are solved.
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The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:
fig. 1 is a flowchart of a time-series based dense subgraph detection method according to an embodiment of the application;
FIG. 2 is a block diagram of a dense subgraph detection system based on time series according to an embodiment of the application;
FIG. 3 is a schematic diagram of a screening matrix element according to an embodiment of the present application;
fig. 4 is an internal structural diagram of an electronic device according to an embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments provided in the present application without any inventive step are within the scope of protection of the present application. Moreover, it should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another.
Reference in the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the specification. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of ordinary skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments without conflict.
Unless defined otherwise, technical or scientific terms referred to herein shall have the ordinary meaning as understood by those of ordinary skill in the art to which this application belongs. Reference to "a," "an," "the," and similar words throughout this application are not to be construed as limiting in number, and may refer to the singular or the plural. The present application is directed to the use of the terms "including," "comprising," "having," and any variations thereof, which are intended to cover non-exclusive inclusions; for example, a process, method, system, article, or apparatus that comprises a list of steps or modules (elements) is not limited to the listed steps or elements, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus. Reference to "connected," "coupled," and the like in this application is not intended to be limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. Reference herein to "a plurality" means greater than or equal to two. "and/or" describes an association relationship of associated objects, meaning that three relationships may exist, for example, "A and/or B" may mean: a exists alone, A and B exist simultaneously, and B exists alone. Reference herein to the terms "first," "second," "third," and the like, are merely to distinguish similar objects and do not denote a particular ordering for the objects.
The dense subgraph detection method based on the time sequence can be applied to anti-fraud scenes of fund transactions such as banks, finance and the like, and the specific implementation scheme is as follows: constructing a three-dimensional transaction matrix, a time set and a user set based on transaction data, wherein the dimensionality of the three-dimensional transaction matrix comprises: transaction time and user, elements of the three-dimensional transaction matrix include: a transaction amount; then, calculating according to the three-dimensional transaction matrix to obtain a time-dimension transaction sum matrix and a user-dimension transaction sum matrix, and summing the transaction sums in the elements to obtain a first sum value; then, averaging the first summation value through the constructed time set and the user set to obtain an initial dense subgraph abnormal value; and finally, iteratively calculating and updating the abnormal value of the intensive subgraph by a greedy algorithm, recording the abnormal value of the maximum intensive subgraph, outputting a time set and a user set corresponding to the abnormal value of the maximum intensive subgraph as a detection result to obtain an intensive group with abnormal fund transaction, solving the problems of low detection accuracy and long calculation time consumption of the intensive subgraph with abnormal fund transaction in the prior art, automatically segmenting the time dimension by the algorithm when selecting the characteristics, automatically screening abnormal information, more accurately and conveniently detecting the abnormal dimension, improving the accuracy of the analysis result, reducing the financial risk, and quickly calculating a large amount of data on complex linear time by the greedy algorithm to effectively improve the calculation speed.
The present embodiment provides a method for dense subgraph detection based on time series, and fig. 1 is a flowchart of a method for dense subgraph detection based on time series according to an embodiment of the present application, as shown in fig. 1, the flowchart includes the following steps:
step S101, a three-dimensional transaction matrix, a time set and a user set are constructed based on transaction data, wherein the dimensionality of the three-dimensional transaction matrix comprises the following steps: transaction time and user, elements of the three-dimensional transaction matrix include: the transaction amount, optionally, the first dimension of the three-dimensional transaction matrix S is transaction time, which indicates when the user is conducting a transaction; the second dimension is the transfer user and the third dimension is the collection user, wherein the transaction amount is the corresponding value element in the matrix, as shown in table 1, 10 thousands of transfers are made from the transfer user 0 to the collection user 1, and then the transaction amount 10 is input at the corresponding position of the three-dimensional transaction matrix S. Optionally, the time set in this embodiment
Figure 742772DEST_PATH_IMAGE003
Indicating how many transaction times are contained in the current set, and the initial value is to contain all time values. For example, if there are two total transactions at 10:00 and 10:10, respectively, then
Figure 411650DEST_PATH_IMAGE010
(ii) a The user set includes, but is not limited to, a transfer user set and a collection of receiving users, and the transfer user set
Figure 467331DEST_PATH_IMAGE004
Indicating how many users the transfer user currently contains, beginning withThe starting value is the value that contains all users, e.g., the transferring users have 0, 1, 2, 3, respectively, then
Figure 690502DEST_PATH_IMAGE011
(ii) a Collection of payee users
Figure 489831DEST_PATH_IMAGE005
Indicating how many users the payee currently contains, and the initial value contains all users, e.g. the payee has 0, 1, 2, 3, respectively, then
Figure 13216DEST_PATH_IMAGE012
(ii) a Taking a bank transaction as an example, at 10:00, 0 user transfers 10 ten thousands, 9 ten thousands and 8 ten thousands yuan to 1, 2 and 3 users respectively, at 10:10, 2 user transfers 2 ten thousands to 3 user, as shown in table 1 below, a three-dimensional transaction matrix S with a dimension of (2,4,4) is constructed, wherein the first dimension 2 represents that 2 transaction times are 10:00 and 10:10, and the second and third dimensions 4 represent that there are transfer users 0, 1, 2, 3 and collection users 0, 1, 2, 3 respectively, and the matrix S is shown in the following formula (1):
Figure 911902DEST_PATH_IMAGE013
TABLE 1
Time of day Transfer user User of collection Transfer amount
10:00 0 1 10w
10:00 0 2 9w
10:00 0 3 8w
10:10 2 3 2w
Compared with the prior art that the fund transaction abnormity detection algorithm is based on users, commodities and abnormity consideration between the users, the feedback result of the fund abnormal transaction cannot be obtained through real-time detection, and the problems of large calculation amount and long consumed time exist, the time dimension is added in the embodiment, when the characteristics are selected, the time dimension is automatically segmented, the abnormal information is automatically screened out, and the detection accuracy of the abnormal group is improved;
step S102, a time-dimension transaction sum matrix and a user-dimension transaction sum matrix are obtained through calculation according to the three-dimensional transaction matrix, and transaction amounts in the three-dimensional transaction matrix are summed to obtain a first sum value. Optionally, the time dimension transaction sum matrix in this embodiment
Figure 950265DEST_PATH_IMAGE014
Meaning the sum of the amounts involved at different transaction times, e.g.,
Figure 490968DEST_PATH_IMAGE015
the sum of the transaction amounts related to the transaction time 0 and the transaction time 1 is respectively 27 ten thousand and 2 ten thousand; user dimension transaction sum matrix including, but not limited to, transfer user dimension transaction sum matrix
Figure 603280DEST_PATH_IMAGE016
Transaction sum matrix with payee dimension
Figure 764DEST_PATH_IMAGE017
Wherein the transaction amount sum matrix of the transfer user dimension
Figure 198527DEST_PATH_IMAGE016
Indicates the total amount of transaction money transferred by the different transfer users, for example,
Figure 542920DEST_PATH_IMAGE018
representing the sum of the money transferred by the transfer users 0, 1, 2 and 3 respectively; transaction amount sum matrix of payee dimensions
Figure 837635DEST_PATH_IMAGE017
Indicating the total amount of the transaction received by the different payee users, e.g.,
Figure 78124DEST_PATH_IMAGE019
representing the total amount of the transaction received by the respective payee 0, 1, 2, 3; first sum value
Figure 102798DEST_PATH_IMAGE001
Representing the sum of the transaction amounts involved in the time dimension, transfer user dimension and collection user dimension of the three-dimensional transaction matrix, resulting in a total transaction amount, e.g.,
Figure 719724DEST_PATH_IMAGE020
the first sum is the sum of the transaction amount of 10 thousands, 9 thousands and 8 thousands transferred from the transfer user 0 to the receiving users 1, 2 and 3 respectively and 2 thousands transferred from the transfer user 2 to the receiving user 3 at the transaction time 0 and 129;
And step S103, averaging the first summation values through the time set and the user set to obtain an initial dense subgraph abnormal value. Optionally, in this embodiment, the first summation value obtained in step S102 is averaged through the total number of elements in the time set and the user set to obtain an initial dense subgraph abnormal value, for example, the time set obtained through calculation is obtained
Figure 868946DEST_PATH_IMAGE021
User collection of account transfers
Figure 280336DEST_PATH_IMAGE011
And collection of payee users
Figure 515008DEST_PATH_IMAGE012
2+4+4=10, on the first summation value obtained in step S102
Figure 935625DEST_PATH_IMAGE020
Averaging to obtain initial dense subgraph abnormal values
Figure 939353DEST_PATH_IMAGE022
Step S104, performing iterative computation and updating of the initial dense subgraph abnormal value through a greedy algorithm, recording the maximum dense subgraph abnormal value therein, and outputting a time set and a user set corresponding to the maximum dense subgraph abnormal value as a detection result, optionally, in the embodiment, the initial dense subgraph abnormal value is updated through the iterative computation of the greedy algorithm, wherein the iterative computation step includes: acquiring a minimum element in a time-dimension transaction sum matrix and a user-dimension transaction sum matrix to obtain a minimum value; then, screening out the corresponding elements of the minimum elements in the time set or the user set to obtain a new time set or a new user set; then, a second summation value is obtained through the minimum value calculation, and the second summation value is averaged through a new time set and a user set to obtain an updated dense subgraph abnormal value; and finally, reconstructing the three-dimensional transaction matrix, recalculating through the newly-established three-dimensional transaction matrix to obtain a new time-dimension transaction sum matrix and a user-dimension transaction sum matrix, and iteratively calculating the steps until one of the time-dimension transaction sum matrix and the user-dimension transaction sum matrix is an empty set. After the iterative computation is completed, recording a maximum dense subgraph abnormal value obtained in the iterative computation, wherein a time set and a user set corresponding to the maximum dense subgraph abnormal value are final abnormal dense groups, and high-risk abnormal operation exists;
in some embodiments, the specific iterative computation process for updating the initial dense subgraph abnormal value by greedy algorithm iterative computation is as follows: taking bank transaction as an example, a time-dimension transaction sum matrix is obtained
Figure 787223DEST_PATH_IMAGE023
Transaction amount sum matrix of transfer user dimension
Figure 712454DEST_PATH_IMAGE024
Transaction sum matrix with payee dimension
Figure 733500DEST_PATH_IMAGE025
Since there is the same minimum element 0, the matrix is randomly selected
Figure 794996DEST_PATH_IMAGE016
The second element 0 in (1) is the total transaction amount transferred by the transfer user 1, corresponding to the user 1 in the transfer user set, and the minimum value is obtained
Figure 876085DEST_PATH_IMAGE026
Then, the corresponding element of the minimum element 0 in the transfer user set is screened out: user 1, get a new set of transfer users
Figure 757453DEST_PATH_IMAGE027
The change is not changed;
finally passes through the minimum
Figure 582190DEST_PATH_IMAGE026
Calculating to obtain a second summation value
Figure 498193DEST_PATH_IMAGE001
As shown in the following formula (5):
Figure 750183DEST_PATH_IMAGE028
, (5)
set of transit times
Figure 384427DEST_PATH_IMAGE029
Collection of users
Figure 950537DEST_PATH_IMAGE030
And a new set of transfer users
Figure 783364DEST_PATH_IMAGE031
Averaging the second summation values to obtain updated dense subgraph abnormal values
Figure 143938DEST_PATH_IMAGE032
As shown in the following formula (6):
Figure 62216DEST_PATH_IMAGE033
(6)
wherein the content of the first and second substances,
Figure 166438DEST_PATH_IMAGE001
is the value of the second sum and,
Figure 119350DEST_PATH_IMAGE004
is a set of users who have new money transfers,
Figure 447564DEST_PATH_IMAGE005
is a collection of users that are to be paid,
Figure 56399DEST_PATH_IMAGE003
is a transaction time set;
calculating to obtain updated dense subgraph abnormal values
Figure 698733DEST_PATH_IMAGE034
Then, before the maximum dense subgraph abnormal value in the updated dense subgraph abnormal values is recorded, a three-dimensional transaction matrix S is reconstructed, and the maximum dense subgraph abnormal value in the matrix S is recorded
Figure 506152DEST_PATH_IMAGE035
All rows in (1) are set to 0, i.e.
Figure 208529DEST_PATH_IMAGE036
And recalculating to obtain a time-dimension transaction sum matrix through the newly-established three-dimensional transaction matrix S
Figure 101399DEST_PATH_IMAGE037
Transaction amount sum matrix of transfer user dimension
Figure 547424DEST_PATH_IMAGE038
Transaction sum matrix with payee dimension
Figure 474928DEST_PATH_IMAGE039
Using the obtained new time dimension transaction sum matrix
Figure 348206DEST_PATH_IMAGE014
Transaction amount sum matrix of transfer user dimension
Figure 462793DEST_PATH_IMAGE016
Transaction sum matrix with payee dimension
Figure 978088DEST_PATH_IMAGE017
Repeating the iterative calculation process until the transaction sum matrix of the time dimension
Figure 697782DEST_PATH_IMAGE014
Transaction amount sum matrix of transfer user dimension
Figure 804278DEST_PATH_IMAGE016
Transaction sum matrix with payee dimension
Figure 343844DEST_PATH_IMAGE017
Until at least one of them is empty, e.g.
Figure 193989DEST_PATH_IMAGE040
After the iterative computation is completed, recording the maximum dense subgraph abnormal value obtained in the iterative computation, wherein the maximum dense subgraph abnormal value is determined by judging conditions, namely the updated dense subgraph abnormal value is obtained in the iterative computation
Figure 33769DEST_PATH_IMAGE032
Comparison of
Figure 248849DEST_PATH_IMAGE008
And
Figure 603607DEST_PATH_IMAGE032
if the numerical value in between
Figure 929546DEST_PATH_IMAGE032
Is greater than
Figure 686150DEST_PATH_IMAGE008
Then remain updated
Figure 72132DEST_PATH_IMAGE032
For example, comparing the initial dense subgraph abnormal values obtained in step S2
Figure 851869DEST_PATH_IMAGE041
And the new dense subgraph abnormal value obtained by updating in the step S5
Figure 43816DEST_PATH_IMAGE042
Due to the magnitude of
Figure 592609DEST_PATH_IMAGE032
Greater than initially
Figure 211809DEST_PATH_IMAGE008
Is thus recorded
Figure 478842DEST_PATH_IMAGE043
And carrying out iterative comparison in such a way until the whole iterative computation is finished, recording a finally reserved value which is the maximum dense subgraph abnormal value, and recording a time set corresponding to the maximum dense subgraph abnormal value
Figure 412163DEST_PATH_IMAGE003
User collection of account transfers
Figure 877780DEST_PATH_IMAGE004
And collection of payee users
Figure 871143DEST_PATH_IMAGE005
The three obtained sets are final abnormal dense groups;
in this embodiment, a transaction sum matrix of time dimensions is iteratively screened through a greedy algorithm
Figure 359894DEST_PATH_IMAGE014
Transaction amount sum matrix of transfer user dimension
Figure 159222DEST_PATH_IMAGE016
Transaction sum matrix with payee dimension
Figure 417028DEST_PATH_IMAGE017
Calculating the minimum value of the data to obtain an updated dense subgraph abnormal value until the updated dense subgraph abnormal value is obtained
Figure 378031DEST_PATH_IMAGE014
Figure 619657DEST_PATH_IMAGE016
And
Figure 894780DEST_PATH_IMAGE017
one of the three matrixes is an empty set, iteration is finished, and the maximum dense subgraph abnormal value obtained in iterative computation is recorded. Compared with the prior art that the subgraph is solved by violence, the time complexity is
Figure 69410DEST_PATH_IMAGE044
The embodiment screens through a greedy algorithm
Figure 670155DEST_PATH_IMAGE014
Figure 867918DEST_PATH_IMAGE016
And
Figure 9050DEST_PATH_IMAGE017
the minimum value in the sub-graph is deleted and then the sub-graph is solved, and the complexity of the computation time is
Figure 975869DEST_PATH_IMAGE045
The method has the advantages that the complexity of linear time is obviously reduced, the calculation time is greatly reduced, the calculation of a large amount of data is greatly advantageous, the calculation time and memory resources can be effectively saved, and the calculation speed is increased. In addition, the abnormal intensive group with high-risk operation can be effectively screened out through the iterative computation, so that the monitoring of abnormal users and abnormal operation by financial institutions such as banks and the like is facilitated, and the financial risk is reduced.
Through the steps S101 to S104, compared with the prior art, the fund transaction anomaly detection algorithm is based on the user and the commodity, and the anomaly consideration between the user and the user, and there are problems that the feedback result of the fund anomaly transaction cannot be detected in real time, the calculation amount is large, and the consumed time is long. The embodiment detects an abnormally-dense subgraph in a time dimension, and constructs a three-dimensional transaction matrix, a time set and a user set based on transaction data, wherein the dimension of the three-dimensional transaction matrix comprises: transaction time and user, elements of the three-dimensional transaction matrix include: a transaction amount; then, calculating according to the three-dimensional transaction matrix to obtain a time-dimension transaction sum matrix and a user-dimension transaction sum matrix, and summing the transaction sums in the elements to obtain a first sum value; then, averaging the first summation value through the constructed time set and the user set to obtain an initial dense subgraph abnormal value; and finally, iteratively calculating and updating the abnormal value of the intensive subgraph by a greedy algorithm, recording the obtained maximum abnormal value of the intensive subgraph, outputting a time set and a user set corresponding to the maximum abnormal value of the intensive subgraph as a detection result to obtain an intensive group with abnormal fund transaction, solving the problems of low detection accuracy and long calculation time consumption of the intensive subgraph with abnormal fund transaction in the prior art, automatically segmenting the time dimension by the algorithm when selecting the characteristics, automatically screening abnormal information, more accurately and conveniently detecting the abnormal dimension, improving the accuracy of the analysis result, reducing the financial risk, quickly calculating a large amount of data on complex linear time by the greedy algorithm, and effectively improving the calculation speed.
In some embodiments, all elements in the three-dimensional transaction matrix are summed to obtain a first summation value
Figure 747516DEST_PATH_IMAGE001
As shown in the following formula (2):
Figure 494892DEST_PATH_IMAGE046
(2)
wherein the content of the first and second substances,
Figure 111818DEST_PATH_IMAGE003
is a set of transaction times that are,
Figure 464302DEST_PATH_IMAGE004
is a set of users who transfer money,
Figure 203588DEST_PATH_IMAGE005
is to receiveA set of users, S is a three-dimensional transaction matrix,
Figure 375943DEST_PATH_IMAGE007
is an empirical anomaly score, optionally an empirical anomaly score
Figure 62139DEST_PATH_IMAGE007
And the transaction time
Figure 65867DEST_PATH_IMAGE003
Related to the user, wherein the transaction is abnormal within a preset time, and the experience abnormal score is
Figure 913738DEST_PATH_IMAGE007
If the user is a white list user, the experience abnormal score is larger than 0
Figure 635706DEST_PATH_IMAGE007
Less than 0, the specific value is determined empirically, e.g., if 0-6 transactions are at a higher risk, then the time period
Figure 860014DEST_PATH_IMAGE007
A value greater than 0, wherein if the transaction spans a time period, such as transaction times of 10:00 and 1:00, then 1:00 is at a time period with a greater risk of transaction between 0 and 6 points, the first summation value
Figure 921511DEST_PATH_IMAGE001
Needs to add one
Figure 737020DEST_PATH_IMAGE007
Values, e.g. user-defined
Figure 149547DEST_PATH_IMAGE047
And when the 10:00 is not in the time period with larger transaction risk of 0-6 points, the addition is not needed; for some users considered normal, such as white-listed users, the risk of white-listed users is lower, so
Figure 911967DEST_PATH_IMAGE007
Can be customized to be negative, e.g., if B1 is a white-listed user among users { A1, A2, A3, B1}, then the first summation value is calculated
Figure 890287DEST_PATH_IMAGE001
When necessary, a negative one is added
Figure 79960DEST_PATH_IMAGE007
Value, e.g.
Figure 714203DEST_PATH_IMAGE048
(ii) a Conversely, if it is a blacklisted user, it is self-defined because of the higher risk
Figure 77052DEST_PATH_IMAGE007
Is positive and the value can be set higher, e.g., B1 is a blacklisted user among users { A1, A2, A3, B1}, then the first summation value is calculated
Figure 113141DEST_PATH_IMAGE001
When necessary, a positive one is added
Figure 739294DEST_PATH_IMAGE007
Value, e.g.
Figure 657572DEST_PATH_IMAGE049
(ii) a Further, if black and white users exist among all users, such as users B1 and B2 among users { A1, A2, A3, B1, B2, C1} are white users and C1 is a black list user, the first sum value is calculated
Figure 761794DEST_PATH_IMAGE001
When necessary to add
Figure 917969DEST_PATH_IMAGE007
Has a value of
Figure 511761DEST_PATH_IMAGE050
And
Figure 855018DEST_PATH_IMAGE051
the sum of the values,
namely, it is
Figure 762931DEST_PATH_IMAGE052
(ii) a If the black-and-white list users exist in the users in the time period with the transaction time of 0-6 points and the transaction risk is large, the users in the black-and-white list exist
Figure 570350DEST_PATH_IMAGE053
Figure 272727DEST_PATH_IMAGE054
Figure 165596DEST_PATH_IMAGE055
All need to be customized according to the above rules, and sum is carried out to obtain the final product
Figure 877200DEST_PATH_IMAGE007
Value is added to the first summation value
Figure 476809DEST_PATH_IMAGE001
In the formula (2).
Taking the bank transaction mentioned in steps S101 and S102 as an example, summing all the elements in the three-dimensional transaction matrix S to obtain a first sum value
Figure 412404DEST_PATH_IMAGE056
In some embodiments, the obtained first summation value is averaged through the time set and the user set to obtain a first dense subgraph abnormal value
Figure 995832DEST_PATH_IMAGE008
As shown in the following formula (3):
Figure 245548DEST_PATH_IMAGE057
(3)
wherein the content of the first and second substances,
Figure 761980DEST_PATH_IMAGE003
is a set of transaction times that are,
Figure 71738DEST_PATH_IMAGE004
is a set of users who transfer money,
Figure 876883DEST_PATH_IMAGE005
is a collection of users that are to be paid,
Figure 727028DEST_PATH_IMAGE001
is a first summation value;
taking the bank transaction mentioned in steps S101 and S102 as an example, the first summation value obtained by averaging the total number of elements in the time set and the user set is used to obtain a first dense subgraph abnormal value
Figure 301228DEST_PATH_IMAGE008
As shown in the following formula (4):
Figure 781888DEST_PATH_IMAGE058
(4)
wherein the numerator is a first summation value
Figure 136646DEST_PATH_IMAGE001
And denominators are the total number 10 of elements of the time set element number 2, the transfer user set element number 4 and the receipt user set element number 4.
In some of these embodiments, after the time dimension transaction amount sum matrix and the user dimension transaction amount sum matrix are obtained, an N-ary tree of the time dimension transaction amount sum matrix and the user dimension transaction amount sum matrix is constructed. Optionally, a node and an N-ary tree corresponding to the node are constructed, when other nodes are removed, the node corresponding to the node is updated, the node corresponding to the minimum element can be found more conveniently and rapidly by searching the matrix in the tree construction mode, the calculation efficiency is improved, and in addition, the node corresponding to the minimum element can also be found in a direct table searching modeFind the smallest element in the matrix. Preferably, the matrix of transaction sums over a time dimension
Figure 462585DEST_PATH_IMAGE015
Constructing a binary tree by using the matrix, and constructing a transaction sum matrix of the dimensions of the transfer users
Figure 156872DEST_PATH_IMAGE024
Constructing a quadtree, when removed
Figure 870750DEST_PATH_IMAGE016
When the second element in the matrix is 0, updating the score corresponding to the node to obtain
Figure 384908DEST_PATH_IMAGE059
Figure 576855DEST_PATH_IMAGE060
And
Figure 391227DEST_PATH_IMAGE061
it should be noted that the steps illustrated in the above-described flow diagrams or in the flow diagrams of the figures may be performed in a computer system, such as a set of computer-executable instructions, and that, although a logical order is illustrated in the flow diagrams, in some cases, the steps illustrated or described may be performed in an order different than here.
The embodiment also provides a system for dense subgraph detection based on time series, which is used for implementing the above embodiments and preferred embodiments, and the description of the system is omitted. As used hereinafter, the terms "module," "unit," "subunit," and the like may implement a combination of software and/or hardware for a predetermined function. Although the means described in the embodiments below are preferably implemented in software, an implementation in hardware, or a combination of software and hardware is also possible and contemplated.
Fig. 2 is a block diagram of a dense subgraph detection system based on time series according to an embodiment of the present application, and as shown in fig. 2, the system includes a construction module 21, a calculation module 22, and an output module 23:
a building module 21, configured to build a three-dimensional transaction matrix, a time set, and a user set based on transaction data, where dimensions of the three-dimensional transaction matrix include: transaction time and user, elements of the three-dimensional transaction matrix include: a transaction amount; the calculation module 22 is used for calculating a transaction sum matrix of a time dimension and a transaction sum matrix of a user dimension according to the three-dimensional transaction matrix, summing transaction sums in the elements to obtain a first sum value, and averaging the first sum value through the time set and the user set to obtain a first dense subgraph abnormal value; and the output module 23 is configured to iteratively calculate and update the dense subgraph abnormal value through a greedy algorithm, record the maximum dense subgraph abnormal value in the updated dense subgraph abnormal value, and output a time set and a user set corresponding to the maximum dense subgraph abnormal value as detection results.
Through the system, compared with the prior art that the fund transaction abnormity detection algorithm is based on users, commodities and abnormity consideration between the users, the feedback result of the fund abnormal transaction cannot be obtained through real-time detection, the problems of large calculation amount and long consumed time exist, the time dimension is added in the embodiment, when the characteristics are selected, the time dimension is automatically segmented, the abnormity information is automatically screened out, and the detection accuracy of the abnormity group is improved; the calculation module 22 calculates a time-dimension transaction sum matrix and a user-dimension transaction sum matrix according to the three-dimensional transaction matrix, sums the transaction amounts in the elements to obtain a first sum value, and averages the first sum value through a time set and a user set to obtain a first dense subgraph abnormal value; compared with the prior art in which subgraph is solved by violence, the output module 23 needs time complexity of
Figure 948110DEST_PATH_IMAGE044
This example screens through a greedy algorithm
Figure 11881DEST_PATH_IMAGE014
Figure 210782DEST_PATH_IMAGE016
And
Figure 614081DEST_PATH_IMAGE017
the minimum value in the sub-graph is deleted and then the sub-graph is solved, and the complexity of the computation time is
Figure 404183DEST_PATH_IMAGE045
The method has the advantages that the complexity of linear time is obviously reduced, the calculation time is greatly reduced, the calculation of a large amount of data is greatly advantageous, the calculation time and memory resources can be effectively saved, and the calculation speed is increased. In addition, the abnormal intensive group with high-risk operation can be effectively screened out through the iterative computation, so that the monitoring of abnormal users and abnormal operation by financial institutions such as banks and the like is facilitated, and the financial risk is reduced.
The present invention will be described in detail with reference to the following application scenarios.
The invention aims to provide a method and a system for dense subgraph detection based on a time sequence, and the flow steps of the technical scheme for dense subgraph detection based on the time sequence in the embodiment comprise:
s1, taking bank transaction as an example, as shown in Table 1, a three-dimensional transaction matrix S and a time set are constructed
Figure 158512DEST_PATH_IMAGE062
User collection of account transfers
Figure 629945DEST_PATH_IMAGE063
And collection of payee users
Figure 950067DEST_PATH_IMAGE064
S2, calculating the transaction amount according to the transaction time and the user in the three-dimensional transaction matrix to obtain a transaction amount sum matrix of time dimension
Figure 379912DEST_PATH_IMAGE023
Transaction amount sum matrix of transfer user dimension
Figure 355958DEST_PATH_IMAGE024
Transaction sum matrix with payee dimension
Figure 427819DEST_PATH_IMAGE065
And summing all elements in the three-dimensional transaction matrix S to obtain a first summation value
Figure 71290DEST_PATH_IMAGE056
Through time aggregation
Figure 140877DEST_PATH_IMAGE003
User collection of account transfers
Figure 666537DEST_PATH_IMAGE004
And collection of payee users
Figure 479772DEST_PATH_IMAGE005
For the first summation value
Figure 977749DEST_PATH_IMAGE001
Averaging to obtain initial dense subgraph abnormal values
Figure 546134DEST_PATH_IMAGE066
S3, obtaining
Figure 231193DEST_PATH_IMAGE014
Figure 113698DEST_PATH_IMAGE016
Figure 262920DEST_PATH_IMAGE017
The smallest element, if there is the same smallest element, randomly selects one. Selecting
Figure 939889DEST_PATH_IMAGE016
Second inElement 0, get the minimum value
Figure 174561DEST_PATH_IMAGE026
S4, due to
Figure 595178DEST_PATH_IMAGE016
The second element in the list corresponds to transfer user 1, so that the transfer users are collected
Figure 802169DEST_PATH_IMAGE004
The second element in the solution is screened out to obtain a new
Figure 712356DEST_PATH_IMAGE067
,
Figure 637587DEST_PATH_IMAGE068
Invariably, FIG. 3 is a schematic diagram of the elements of the screening matrix according to an embodiment of the application, as shown in FIG. 3, due to the set of transfer users
Figure 596315DEST_PATH_IMAGE004
The second element 1 in (a) is screened out, thus the three-dimensional transaction matrix S neutralizes
Figure 454550DEST_PATH_IMAGE069
All elements concerned are absent and should be removed;
s5, passing through the minimum value
Figure 738901DEST_PATH_IMAGE026
Recalculating to obtain a second sum average
Figure 885848DEST_PATH_IMAGE070
Through a new set of transfer users
Figure 710585DEST_PATH_IMAGE031
Constant, and constant
Figure 626588DEST_PATH_IMAGE068
For the second summation valueLine averaging to obtain updated dense subgraph abnormal value
Figure 816261DEST_PATH_IMAGE071
S6, recalculating the three-dimensional transaction matrix S and dividing the three-dimensional transaction matrix S into S matrices
Figure 512822DEST_PATH_IMAGE035
All rows in (1) are set to 0, i.e.
Figure 813353DEST_PATH_IMAGE072
And then recalculated according to S3
Figure 115021DEST_PATH_IMAGE073
Figure 272333DEST_PATH_IMAGE061
Figure 393873DEST_PATH_IMAGE037
S7, judgment
Figure 560412DEST_PATH_IMAGE016
Figure 451008DEST_PATH_IMAGE017
Figure 982483DEST_PATH_IMAGE014
Whether or not there is an empty set, e.g.
Figure 388057DEST_PATH_IMAGE040
If not, continuing to execute S3, and if yes, executing S8;
s8, recording the maximum dense subgraph abnormal value obtained in the iterative computation after the iteration is finished, wherein the maximum dense subgraph abnormal value is determined by judging conditions, namely the updated dense subgraph abnormal value is obtained in the iterative computation
Figure 295970DEST_PATH_IMAGE032
Comparison of
Figure 306651DEST_PATH_IMAGE008
And
Figure 71345DEST_PATH_IMAGE032
if the numerical value in between
Figure 901898DEST_PATH_IMAGE032
Is greater than
Figure 613502DEST_PATH_IMAGE008
Then remain updated
Figure 275427DEST_PATH_IMAGE032
E.g., comparing the initial dense subgraph outliers obtained in step S2
Figure 148705DEST_PATH_IMAGE041
And the new dense subgraph abnormal value obtained by updating in the step S5
Figure 528871DEST_PATH_IMAGE042
The numerical value in between, because
Figure 778587DEST_PATH_IMAGE032
Greater than initially
Figure 498281DEST_PATH_IMAGE008
Is thus recorded
Figure 604777DEST_PATH_IMAGE043
The iterative comparison is carried out until the iterative computation from S3 to S7 is finished, and the record retains the final value which is the maximum dense subgraph abnormal value
Figure 409922DEST_PATH_IMAGE008
That is, the final output risk score is obtained, wherein the transfer user set corresponding to the maximum dense subgraph abnormal value
Figure 463329DEST_PATH_IMAGE004
Set of payee users
Figure 99847DEST_PATH_IMAGE005
And time aggregation
Figure 314927DEST_PATH_IMAGE074
Is the exception group that is ultimately output.
Results in the above example:
Figure 607369DEST_PATH_IMAGE075
Figure 272923DEST_PATH_IMAGE076
Figure 701630DEST_PATH_IMAGE077
Figure 149929DEST_PATH_IMAGE078
(ii) a That is, user 0 given 1, 2, 3 transfers at time 0, i.e., 10, is an unusually dense group with a high risk score of 5.4.
The present embodiment also provides an electronic device comprising a memory having a computer program stored therein and a processor configured to execute the computer program to perform the steps of any of the above method embodiments.
Optionally, the electronic apparatus may further include a transmission device and an input/output device, wherein the transmission device is connected to the processor, and the input/output device is connected to the processor.
In addition, in combination with the method for dense subgraph detection based on time series in the above embodiments, the embodiments of the present application may provide a storage medium to implement. The storage medium having stored thereon a computer program; the computer program, when executed by a processor, implements any one of the methods of time-series based dense subgraph detection in the above embodiments.
In one embodiment, fig. 4 is a schematic diagram of an internal structure of an electronic device according to an embodiment of the present application, and as shown in fig. 4, there is provided an electronic device, which may be a server, and its internal structure diagram may be as shown in fig. 4. The electronic device includes a processor, a memory, a network interface, and a database connected by a system bus. Wherein the processor of the electronic device is configured to provide computing and control capabilities. The memory of the electronic equipment comprises a nonvolatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of an operating system and computer programs in the non-volatile storage medium. The database of the electronic device is used for storing data. The network interface of the electronic device is used for connecting and communicating with an external terminal through a network. The computer program is executed by a processor to implement a method of dense subgraph detection based on time series.
Those skilled in the art will appreciate that the configuration shown in fig. 4 is a block diagram of only a portion of the configuration associated with the present application, and does not constitute a limitation on the electronic device to which the present application is applied, and a particular electronic device may include more or less components than those shown in the drawings, or combine certain components, or have a different arrangement of components.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware instructions of a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in the embodiments provided herein may include non-volatile and/or volatile memory, among others. Non-volatile memory can include read-only memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), Rambus Direct RAM (RDRAM), direct bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).
It should be understood by those skilled in the art that various features of the above-described embodiments can be combined in any combination, and for the sake of brevity, all possible combinations of features in the above-described embodiments are not described in detail, but rather, all combinations of features which are not inconsistent with each other should be construed as being within the scope of the present disclosure.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. A method of dense subgraph detection based on time series, the method comprising:
constructing a three-dimensional transaction matrix, a time set and a user set, wherein the dimensionality of the three-dimensional transaction matrix comprises the following steps: transaction time and user, the elements of the three-dimensional transaction matrix comprising: a transaction amount;
calculating to obtain a time-dimension transaction sum matrix and a user-dimension transaction sum matrix according to the three-dimensional transaction matrix, and summing the transaction sums in the elements to obtain a first sum value;
averaging the first summation value through the time set and the user set to obtain an initial dense subgraph abnormal value;
and iteratively calculating and updating the dense subgraph abnormal value through a greedy algorithm, recording the obtained maximum dense subgraph abnormal value, and outputting a time set and a user set corresponding to the maximum dense subgraph abnormal value as detection results.
2. The method of claim 1, wherein summing the transaction amounts in the element results in a first summed value
Figure DEST_PATH_IMAGE001
Figure DEST_PATH_IMAGE002
Wherein the content of the first and second substances,
Figure DEST_PATH_IMAGE003
is a set of transaction times that are,
Figure DEST_PATH_IMAGE004
is a set of users who transfer money,
Figure DEST_PATH_IMAGE005
is a collection of payee users, S is a three-dimensional transaction matrix,
Figure DEST_PATH_IMAGE006
is the empirical anomaly score.
3. The method of claim 2, wherein the empirical anomaly score comprises:
the experience anomaly score is related to the transaction time and the user, wherein the transaction is anomalous within a preset time, the experience anomaly score is greater than 0, and when the user is a white list user, the experience anomaly score is less than 0.
4. The method of claim 1, wherein the first summation value is summed over the set of times and the set of usersLine averaging is carried out to obtain an initial intensive subgraph abnormal value
Figure DEST_PATH_IMAGE007
Figure DEST_PATH_IMAGE008
Wherein the content of the first and second substances,
Figure 890881DEST_PATH_IMAGE003
is a set of transaction times that are,
Figure 542442DEST_PATH_IMAGE004
is a set of users who transfer money,
Figure 56600DEST_PATH_IMAGE005
is a collection of users that are to be paid,
Figure 186230DEST_PATH_IMAGE001
is the first summation value.
5. The method of claim 1, wherein the iteratively computing and updating the dense subgraph outliers by a greedy algorithm comprises:
acquiring a minimum element in the time-dimension transaction sum matrix and the user-dimension transaction sum matrix to obtain a minimum value;
screening out the corresponding elements of the minimum elements in the time set or the user set to obtain a new time set or a new user set;
calculating to obtain a second summation value through the minimum value, and averaging the second summation value through the new time set and the user set to obtain an updated dense subgraph abnormal value;
and recalculating the three-dimensional transaction matrix, and recalculating the new time-dimension transaction sum matrix and the user-dimension transaction sum matrix through the new three-dimensional transaction matrix.
6. The method of claim 5, wherein after recalculating the transaction sum matrix for the new time dimension and the transaction sum matrix for the user dimension, the method comprises:
judging whether an empty set exists in the transaction sum matrix of the new time dimension and the transaction sum matrix of the user dimension;
in the case where there is an empty set, the iterative computation terminates.
7. The method of claim 1, wherein after obtaining the transaction sum matrix in the time dimension and the transaction sum matrix in the user dimension, the method comprises:
and constructing an N-branch tree of the transaction sum matrix of the time dimension and the transaction sum matrix of the user dimension.
8. A system for dense subgraph detection based on time series, the system comprising:
the construction module is used for constructing a three-dimensional transaction matrix, a time set and a user set, wherein the dimensionality of the three-dimensional transaction matrix comprises the following steps: transaction time and user, the elements of the three-dimensional transaction matrix comprising: a transaction amount;
a calculation module for calculating a time dimension transaction sum matrix and a user dimension transaction sum matrix according to the three-dimensional transaction matrix, and summing the transaction amounts in the elements to obtain a first sum value,
averaging the first summation value through the time set and the user set to obtain an initial dense subgraph abnormal value;
and the output module is used for iteratively calculating and updating the dense subgraph abnormal value through a greedy algorithm, recording the obtained maximum dense subgraph abnormal value, and outputting a time set and a user set corresponding to the maximum dense subgraph abnormal value as detection results.
9. An electronic device comprising a memory and a processor, wherein the memory has stored therein a computer program, and the processor is configured to execute the computer program to perform the method for time-series based dense subgraph detection according to any one of claims 1 to 7.
10. A storage medium, in which a computer program is stored, wherein the computer program is arranged to perform the method for time-series based dense subgraph detection according to any one of claims 1 to 7 when running.
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