# Bug in ideals triggered by trying to find maximal subsemigroups

Issue #103 resolved
James Mitchell
repo owner created an issue
```gap> S:=POI(5);
<inverse partial perm monoid on 5 pts with 5 generators>
gap> T:=Semigroup(S, PartialPerm([1,2,3,4,5],[2,3,4,5,1]));
<partial perm monoid on 5 pts with 11 generators>
gap> MaximalSubsemigroups(T);
Error, no method found! For debugging hints type ?Recovery from NoMethodFound
Error, no 1st choice method found for `Enumerate' on 3 arguments called from
Enumerate( SemigroupData( o!.parent ), infinity, newlookfunc ); called from
Enumerate( o, infinity ); called from
Size( C ) called from
IsEmpty( V ) called from
<function "unknown">( <arguments> )
called from read-eval loop at line 9 of *stdin*
you can 'quit;' to quit to outer loop, or
you can 'return;' to continue
brk>
```

1. reporter

A simplified example where the same thing happens is:

```gap> S:=POI(5);;
gap> T:=Semigroup(S, PartialPerm([1,2,3,4,5],[2,3,4,5,1]));;
gap> I:=SemigroupIdeal(T, [ PartialPerm( [ 1, 2, 4, 5 ], [ 1, 2, 3, 5 ] )]);
<inverse partial perm semigroup ideal on 5 pts with 1 generator>
gap> Size(I);
Error, no method found! For debugging hints type ?Recovery from NoMethodFound
Error, no 1st choice method found for `Enumerate' on 3 arguments called from
Enumerate( SemigroupData( o!.parent ), infinity, newlookfunc ); called from
Enumerate( o, infinity ); called from
<function "unknown">( <arguments> )
called from read-eval loop at line 7 of *stdin*
you can 'quit;' to quit to outer loop, or
you can 'return;' to continue
brk>
```
2. reporter
• removed milestone

Removing milestone: 2.1 (automated comment)