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thetensor-space / TameGenus

Algorithms for isomorphism testing of groups with small genus
MIT License
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A genus 1 bug #9

Closed joshmaglione closed 5 years ago

joshmaglione commented 5 years ago

E.A. O'Brien communicated the following bug to me.

> G:=PCGroup(\[ 12, -7, 7, 7, 7, 7, 7, 7, 7, -7, 7, 7, 7, 207534602, 207533102\
,
> 1936989603, 434833071, 16948659004, 16948535536, 13277869108, 643372420,
> 142368735605, 31960229633, 5404349189, 245654681, 138503461746, 120993055194\
,
> 20071591710, 2398656666, 397523334, 39242598, 968012207239, 160661474419,
> 19190635999, 1844429035, 313968535, 31319299 ]) ;
>
> > A := TGAutomorphismGroup (G);
Extracting the p-central tensor and computing pseudo-isometries.
Checking the radicals.
        dim(Rad_V) = 0
        dim(Rad_W) = 0

Writing tensor over its centroid.

Tensor has genus 1.

Constructing the pseudo-isometry group.

TGAutomorphismGroup(
    G: GrpPC
)
__TameGenusAutomorphism(
    G: GrpPC
)
TGPseudoIsometryGroup(
    t: Tensor of valence 3, U2 x U1 >-> U0 U2 : Full Vector space o...
)
__G1_PIsometry(
    t: Tensor of valence 3, U2 x U1 >-> U0 U2 : Full Vector space o...,
    H: Maps from U2 x U1 >-> U0 to V2 x V1 >-> V0. U2 -> V2: Mappin...
)
In file "/home/eobr007/Stabiliser/TameGenus/src/PIsomGroup.m", line 39, column
19:
>>     check_lift, G := Lift1(t, t, F, 0);
                     ^
Runtime error in :=: Expected to assign 2 value(s) but only computed 1 value(s)
joshmaglione commented 5 years ago

Possibly a version issue. Will find out soon.

joshmaglione commented 5 years ago

For the record, I cannot reproduce this.

eamonnaobrien commented 5 years ago

Today I pulled latest version of code. I still get exactly this crash ...

joshmaglione commented 5 years ago

I believe the bug lies in StarAlge. Are you on the branch PerpFix inside StarAlge? If not, this will not fixed.

algeboy commented 5 years ago

This seems to be fixed with these changes.

  1. First the function "Lift1" is in a another package (Auto-Sandbox) which is nowhere near publically presentable. So made a local copy of it here. Later if the rightful package of Lift1 is made it can be moved back.
  2. Renamed Lift1 to InducePseudoIsometry.
  3. There was a return at bottom of the function which was missing a parameter.