Dear GAP-Forum,

Diego Rattagi asked:

I have a question about SimsName and IdGroup:

gap> G1 := PrimitiveGroup(10,5);;
gap> SimsName(G1);
"M_10"

While you did not state the version of GAP you are using, I deduce from
this output that it is 4.1.

> What's the reason for this ?
Version 4.1 contains a couple of known bugs in the primitive groups
library. In the current release GAP4.2, the problem you observed is gone:

gap> G1 := PrimitiveGroup(10,5);;
gap> SimsName(G1);
"S(6)"
gap> IdGroup(G1);
[ 720, 763 ]
gap> G2 := PrimitiveGroup(10,6);;
gap> SimsName(G2);
"M_10"
gap> IdGroup(G2);
[ 720, 765 ]

I would therefore strongly urge you to update to the recent version.

Best wishes and apologies for the confusion you encountered,

Alexander Hulpke

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