Factorization algorithm computes incorrect result for some large complex graphs. #66
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…lex graphs. Fixes #65 added new_factor_subgraph! to eventually replace factor_subgraph! changed definition of node_value field in Node to have a Union type instead of Any. May help performance.
…lex graphs. Fixes #65 fixed factor_order. Used to sort by times_used first then by subgraph containment. This was based on an incorrect assumption that the times_used of a subgraph was always greater than or equal to the times_used of a containing subgraph. Now sorts by subgraph containment, then by times_used, so contained subgraphs always get factored first.
This was referenced Apr 25, 2024
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Fixes #65
Factorization can create new factorable subgraphs interior to an existing subgraph. The most general way to solve this problem is to rerun the dominance calculation on each subgraph where this condition is detected and then to recursively factor these subgraphs before factoring the containing subgraph.
This seemed too computationally expensive so I had special case code which appeared to work. But larger graphs tend to also have more complex internal structure which is more likely to give rise to these internal factorable subgraphs. The current code eventually fails as graphs get larger and their structure becomes more convoluted.
This PR will replace the existing algorithm with a dominance recomputation which will be executed only if internal subgraph creation is detected.