It is a (documentation, at least) bug in both GAP 4.4 and in GAP 4.5; in the latter (more precisely, GAP 4.5.4) I get
gap> IrreducibleRepresentations(DihedralGroup(10),GF(2^2)); Error, no method found! For debugging hints type ?Recovery from NoMethodFound Error, no 1st choice method found for `[]' on 2 arguments called from s = 1 called from LiftAbsAndIrredModules( pcgsS, pcgsN, modrec, dim ) called from AbsAndIrredModules( G, F, dim ) called from IrreducibleModules( G, f, 0 ) called from <function "unknown">( <arguments> ) called from read-eval loop at line 5 of *stdin* you can 'quit;' to quit to outer loop, or you can 'return;' to continue brk> Hopefully someone who knows more about the algorithms involved can comment on this, and/or provide a fix. Best, Dmitrii On 13 July 2012 01:38, Neha Makhijani <nehamakhij...@gmail.com> wrote: > It works for fields of non-prime order. But really not able to guess why it > does not work for this particular case. Have a look! > > IrreducibleRepresentations(DihedralGroup(10),GF(2^3)); > [ Pcgs([ f1, f2 ]) -> [ [ [ Z(2)^0 ] ], [ [ Z(2)^0 ] ] ], > Pcgs([ f1, f2 ]) -> [ > [ [ Z(2)^0, 0*Z(2), Z(2^3), Z(2)^0 ], [ 0*Z(2), Z(2)^0, Z(2^3)^6, > Z(2^3)^3 ], [ 0*Z(2), 0*Z(2), Z(2^3), Z(2^3)^3 ], > [ 0*Z(2), 0*Z(2), Z(2^3)^2, Z(2)^0 ] ], > [ [ Z(2^3)^2, Z(2^3)^4, Z(2^3), 0*Z(2) ], > [ Z(2^3)^3, Z(2^3), 0*Z(2), Z(2^3) ], > [ Z(2^3), Z(2^3), Z(2^3)^3, Z(2^3)^5 ], > [ Z(2)^0, 0*Z(2), Z(2^3)^4, Z(2^3)^2 ] ] ] ] > > Neha > > On Thu, Jul 12, 2012 at 10:51 PM, Dmitrii (Dima) Pasechnik <d...@ntu.edu.sg> > wrote: >> >> This looks like a bug (in documentation, at least). >> This command apparently does not work for >> finite fields of non-prime order. >> (but you can still do IrreducibleRepresentations(DihedralGroup(10),GF(2))) >> >> Hope this helps, >> Dmitrii >> >> On 13 July 2012 00:58, Neha Makhijani <nehamakhij...@gmail.com> wrote: >> > Can somebody please clarify as to why I am not able to get the >> > irreducible >> > representations of the dihedral group over GF(4)?? >> > >> > IrreducibleRepresentations(DihedralGroup(10),GF(2^2)); >> > List Element: <position> must be a positive integer (not a boolean) >> > >> > Thanks! >> > >> > Neha >> > _______________________________________________ >> > Forum mailing list >> > Forum@mail.gap-system.org >> > http://mail.gap-system.org/mailman/listinfo/forum >> >> CONFIDENTIALITY:This email is intended solely for the person(s) named and >> may be confidential and/or privileged.If you are not the intended >> recipient,please delete it,notify us and do not copy,use,or disclose its >> content. >> >> Towards A Sustainable Earth:Print Only When Necessary.Thank you. > > > > > -- > Neha Makhijani > Research Scholar > Department of Mathematics > IIT Delhi > _______________________________________________ Forum mailing list Forum@mail.gap-system.org http://mail.gap-system.org/mailman/listinfo/forum