Fix: Prevent oscillation in label propagation algorithm #1086
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- Changed from synchronous to asynchronous updates with randomized node order - Added maximum iteration limit (100) to prevent infinite loops - Implemented oscillation detection with early stopping mechanism - Improved tie-breaking with deterministic sorting - Added detailed logging for convergence and oscillation events The previous implementation used synchronous updates where all nodes updated simultaneously, which could cause oscillation in certain graph structures (e.g., bipartite graphs). This fix ensures the algorithm always terminates and produces stable community assignments.
ZLBillShaw
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ZLBillShaw
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prasmussen15
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Dec 8, 2025
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prasmussen15
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Are you able to fix the failing test case?
- Changed from synchronous to asynchronous updates with randomized node order - Added maximum iteration limit (100) to prevent infinite loops - Implemented oscillation detection with early stopping mechanism - Improved tie-breaking with deterministic sorting - Added detailed docstring and logging for convergence/oscillation events - Fixed oscillation detection to properly break out of nested loops The previous implementation used synchronous updates where all nodes updated simultaneously, which could cause oscillation in certain graph structures (e.g., bipartite graphs). This fix ensures the algorithm always terminates and produces stable community assignments while maintaining backward compatibility with existing tests.
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Yes, I've fixed the failing test case. |
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Summary
Fixed infinite loop bug in label propagation algorithm caused by synchronous updates leading to oscillation in certain graph structures.
Type of Change
Objective
The previous implementation of the label propagation algorithm in
community_operations.pyused synchronous updates where all nodes update their community labels simultaneously. This approach can cause oscillation in certain graph topologies (e.g., bipartite graphs, regular graphs), where nodes continuously swap between two or more community assignments without ever converging, resulting in infinite loops.Root Cause:
Solution:
MAX_ITERATIONS = 100to guarantee termination