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Is FindMaximumFlow function broken?

Posted 6 months ago
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I ran the example on FindMaximumFlow in the documentation and got the following results.

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My guess is that the answer is wrong. Instead of pairing with Billy, Mary can easily connect to Dustin and Alecia can then pair with Billy. When I run the results in Table to get maximum flows value I get 3 or 4. Am I wrong or is there something strange with the FindMaximumFlow function?

Yep, broken, specifically with vertex capacities (not edge capacities). I have a little notebook with some of these bugs. It's been sent to WRI more than once.

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Another bug is that when we request the OptimumFlowData, then certain documented properties cannot be retrieved.

g = RandomGraph[{10, 20}]
fd = FindMaximumFlow[g, 1, 10, "OptimumFlowData"]

Now fd["FlowTable"] and fd["ResidualGraph"] don't work. Retrieving multiple properties also doesn't work, despite being documented: fd[{"CostValue", "EdgeList"}].

Some of these problems actually show in the documentation notebooks. You can also check online, just open Scope, and you'll see the bugs immediately in the Out[] cells.

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There was a recent Twitch stream dealing with Graph stuff, and you can see bug counts mentioned in the meeting notebooks. It sounded as if there were a new drive to eliminate some of these bugs.

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