Abductive Workflow Mining Using Binary Resolution on Task Successor Rules

Scott BuffettNational Research Council Canada

University of New Brunswick

RuleML 2008

Orlando, Florida, October 30, 2008

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Workflow Mining

• Transaction log containing a number of events

• Each event is labeled by a task and a case

• Tasks executed a case give a trace

• ABCE, ABDE, ACBE, ADBE

A E

B

C

D

Task CaseA 1A 2A 3C 3B 1B 2A 4B 3D 2C 1E 1B 4D 4E 2E 3E 4

3

Using Workflow to Measure Compliance

• Compare observed activity with accepted model

• ACDE?

• If discrepancies exist, behavior may be non-compliant

A E

B

C

D

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Problems with Using Workflow

• Detected non-compliant behaviour does not imply inappropriate activity

• Behaviour might be OK, but not captured during workflow mining

• Workflow model not 100% accurate

• Errors in task / case labelings

• Noise

• Process may have evolved or changed

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Solution

• Identify the tasks that are of high importance

• Example process: Bank loan application– A: Enter financial data

– B: Access credit report

– C: Process loan application form

– D: Process pre-approved loan form

– E: Approve loan

– F: Reject loan application

• Cases observed: ABCE, ABCF, ADE

A

B

D

F

E

C

Task B: Access credit report

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Abductive Workflow Mining

• Reduce the problem to mining workflow that necessarily implies that the critical activity must be executed

• We call this “abductive workflow”

A

B

D

F

E

C

Presence of task C (process loan application

form) implies B

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Some Example Abductive Workflows for Critical Task “B”

F

C F

C

F

A B C

A B

C

A

B

D

F

E

C

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Desirable Properties

• Trace minimality:

• Completeness:

A B CC

C

F

C

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Finding Desirable Workflows

• Task successor rules

• Indicate activity that immediately follows certain tasks

• Example workflow traces:– PQR, PRS, RMN, TVQ

• Critical activity: R

10

Divide Positive and Negative Traces

Traces: PQR, PRS, RMN, TVQ, Critical: R

• Positive traces: PQR, PRS, RMN

• Negative traces: TVQ

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Remove Critical Activity

Traces: PQR, PRS, RMN, TVQ, Critical: R

• Positive traces: PQR, PRS, RMN• Remove critical activity: PQ, PS, MN

• Negative traces: TVQ

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Add Dummy Tasks

Traces: PQR, PRS, RMN, TVQ, Critical: R

• Positive traces: PQR, PRS, RMN• Remove critical activity: PQ, PS, MN• Add dummy tasks: PQw’, PSw’, MNw’

• Negative traces: TVQ

• Add dummy tasks: TVQw0’

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Task Successor Rules

• One for every subsentence in positive traces (except w’)

• Positive: PQw’, PSw’, MNw’

• Negative: TVQw0’

• Rules:

P -> Q, S Q -> w’, w0’

S -> w’ M -> N

N -> w’ PQ -> w’

PS -> w’ MN -> w’

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Finding Abductive Workflows

• Convert to CNF

~P, Q, S ~Q, w’, w0’

~S, w’ ~M, N

~N, w’ ~P, ~Q, w’

~P, ~S, w’ ~M, ~N, w’

• Binary resolution, generate clauses where w’ is the only positive literal

P -> w’

~PQS

~Sw’~PSw’

~P~Qw’

~Pw’

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Finishing the Example

• Complete set of abductive traces:– P, S, M, N, PS, MN, PQ

• Task-minimal abductive traces:– P, S, M, N

• Complete workflows:– {P,M}, {P,N}, {P,M,N}, {P,S,M}, {P,S,N}, {P,S,M,N}

• Complete, trace-minimal:– {P,M}, {P,N}

PQR, PRS, RMN

TVQ

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Results

• Test size reduction of abductive workflows• Uses a naïve method for finding abductive workflows, complete

but not necessarily minimal• Thus provides a lower bound on size reduction• Mines entire workflow and extracts abductive workflow • Ran on example log files accompanying ProM software

Our Miner Alpha Miner

Statistic (Avg) Orig. Workflow Abd. Workflow Orig. Workflow Abd. Workflow

# of transitions 156.2 37.2 12.0 5.6

# of arcs 318.6 77.0 33.2 15.6

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Conclusions

• Abductive workflows provide a condensed model, adequate for validating particular critical activity

• Mitigate a number of problems inherent in compliance checking

• Rules can help determine such workflows, with desirable properties

• Potential for significant decreases in size of workflow model was demonstrated

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