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keep the ordering of characters/classes #3581

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merged 2 commits into from
Jul 18, 2019
Merged

keep the ordering of characters/classes #3581

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96d7671
keep the ordering of characters/classes
ThomasBreuer Jul 17, 2019
c149620
added a test that documents the changed behaviour
ThomasBreuer Jul 18, 2019
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added a test that documents the changed behaviour 
(The idea of the change is to guarantee a particular ordering
of conjugacy classes, I have no idea how to express this without
referring to a given class ordering, that is, referring to some
library character table.)
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@ThomasBreuer
ThomasBreuer committed Jul 18, 2019
commit c14962022e81c7ccab0c8d2f0cf0c81b0184f8d2
16 changes: 15 additions & 1 deletion tst/teststandard/ctblisoc.tst
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@@ -1,4 +1,4 @@
#@local g, t, iso, t3, iso3, orders, n, iso2, filt, c
#@local g, t, iso, t3, iso3, orders, n, iso2, filt, outer, c
gap> START_TEST( "ctblisoc.tst" );

# one argument
Expand Down Expand Up @@ -100,6 +100,20 @@ gap> Length( filt );
1
gap> IdGroup( filt[1] ) = IdGroup( g );
false
gap> if TestPackageAvailability( "ctbllib" ) <> fail and
> LoadPackage( "ctbllib", false ) <> fail then
> t:= CharacterTable( "4_1.L3(4).2_3" );
> iso:= CharacterTableIsoclinic( t, [ 1 .. 4 ] );
> outer:= Difference( [ 1 .. NrConjugacyClasses( t ) ],
> ClassPositionsOfDerivedSubgroup( t ) );
> if PowerMap( iso, 2 ){ outer{ [ 1 .. 4 ] } } <> [ 2, 4, 2, 4 ] then
> # If the power map is [ ..., 4, 2, 4, 2, ... ] then
> # the table can be correct, but we want
> # --for example for the library table "4_1.L3(4).2_3*"--
> # that the *first* generator of the centre appears first.
> Error( "wrong ordering of classes for isoclinic table" );
> fi;
> fi;

# optional arguments:
# normal subgroup specified, ...
Expand Down