Membership to numerical semigroups

[pedritomelenas]

The basic (HasGenerators) implementation should be improved, but also in the case the Apéry set is known, it does not use the implementation for HasAperyList.

gap> s:=NumericalSemigroup([ 4, 180738, 234949, 253363 ]);;
gap> a:=AperyList(s);;
gap> x:=373067;;
gap> x in s;
Error, recursion depth trap (5000) in
  belongs( x - gen[1], gen ) at /home/FQM343/pedro/lib/gap-4.11.1/pkg/numericalsgps/gap/basics.gi:690 called from 
belongs( x - gen[1], gen ) at /home/FQM343/pedro/lib/gap-4.11.1/pkg/numericalsgps/gap/basics.gi:690 called from
belongs( x - gen[1], gen ) at /home/FQM343/pedro/lib/gap-4.11.1/pkg/numericalsgps/gap/basics.gi:690 called from
belongs( x - gen[1], gen ) at /home/FQM343/pedro/lib/gap-4.11.1/pkg/numericalsgps/gap/basics.gi:690 called from
belongs( x - gen[1], gen ) at /home/FQM343/pedro/lib/gap-4.11.1/pkg/numericalsgps/gap/basics.gi:690 called from
belongs( x - gen[1], gen ) at /home/FQM343/pedro/lib/gap-4.11.1/pkg/numericalsgps/gap/basics.gi:690 called from
...  at *stdin*:42
you may 'return;'

However, it uses the implementation of HasSmallElements

gap> sm:=SmallElements(s);;
gap> x in s;
true

This is an example produced from an issue reported by @coneill-math .

[pedritomelenas]

Commit 6b3c4fb solves the issue of not using HasAperyList method, though the HasGenerators methods still needs to be polished.

gap> s:=NumericalSemigroup([ 4, 180738, 234949, 253363 ]);;
gap> x:=373067;;
gap> a:=AperyList(s);;
gap> x in s;
true

[pedritomelenas]

It seems that 84204b7 solves the problem. However, I would like to see if performance has changed.

[pedritomelenas]

We are loosing performance

gap> s:=RandomNumericalSemigroup(20,10000);;
gap> gen:=MinimalGenerators(s);
[ 216, 2024, 2507, 4755, 5310, 5398, 5613, 8308, 9496, 9685 ]
gap> belongs(1000000,gen);time;
true
41
gap> bel(1000000,gen);time;    
true
101

But we avoid things like

gap> s:=NumericalSemigroup([ 4, 180738, 234949, 253363 ]);;
gap> gen:=MinimalGenerators(s);
[ 4, 180738, 234949, 253363 ]
gap> x:=373067;;
gap> SetRecursionTrapInterval(30000);;
gap> belongs(x,gen);time;
Violación de segmento (`core' generado)