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Size of fp semigroup is negative #685

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james-d-mitchell opened this issue Jul 3, 2020 · 2 comments
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Size of fp semigroup is negative #685

james-d-mitchell opened this issue Jul 3, 2020 · 2 comments
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@james-d-mitchell
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F := FreeSemigroup(2);
s1 := F.1; s2 := F.2;
rels := [ [ s2*s1*s2, s2*s1 ], [ s1, s1 ], [ s2, s2 ], [ s1*s2, s1*s2 ], [
        s2*s1, s2*s1 ] ];
Size(F / rels); # returns -2!!

This is likely caused by libsemigroups returning that the fp semigroup is infinite, and this getting incorrectly returned as -2 in GAP.
@james-d-mitchell james-d-mitchell added the bug Label for issues or PR which report or fix bugs label Jul 3, 2020
@olexandr-konovalov
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I wonder if Size in GAP should have an assertion to forbid negative sizes...

james-d-mitchell added a commit to james-d-mitchell/Semigroups that referenced this issue Jul 29, 2020
@james-d-mitchell
Resolve Issue semigroups#685
4ca3805
james-d-mitchell added a commit to james-d-mitchell/Semigroups that referenced this issue Jul 29, 2020
@james-d-mitchell
Resolve Issue semigroups#685
3c2491e
james-d-mitchell added a commit to james-d-mitchell/Semigroups that referenced this issue Aug 4, 2020
@james-d-mitchell
Resolve Issue semigroups#685
f41e3a4
james-d-mitchell added a commit that referenced this issue Aug 5, 2020
@james-d-mitchell
Resolve Issue #685
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@james-d-mitchell
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Resolved in v3.4.0

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@olexandr-konovalov @james-d-mitchell