[GAP Forum] Urgent Issue on GAP...

[Dan Rossul]

Yes I dont understand why (3,4)(1) would be fine not (1)(3,4)
Is there any method to make (1)(3,4) executable, no error in GAP?

thanks!


----- Original message -----
From: "Sergei Haller" <Sergei.Haller at math.uni-giessen.de>
To: forum at gap-system.org
Date: Tue, 8 Mar 2005 18:19:46 +0100 (CET)
Subject: Re: [GAP Forum] Urgent Issue on GAP...

On Tue, 8 Mar 2005, Dan Rossul (DR) wrote:

DR> gap> g:=Group((1)(2)(3,4));
DR> Syntax error: ) expected
DR> 
DR> I suppose GAP should understand (1)(2)(3,4) = (3,4)

seems that GAP interprets (1) as the integer 1 in parenthesis:

   gap> (1) in Integers;
   true
   gap> (1) in SymmetricGroup(4);
   false

on the other hand, an expression like "(3,4)(1)" is interpreted in the
way 
you expect it.

for your purpose, you might try something like  "PermList([1,2,4,3]);"

DR> [...] if Syntax error where should I add the )?

if you read the full error message:

   gap> g:=Group((1)(2)(3,4));
   Syntax error: ) expected
   g:=Group((1)(2)(3,4));
               ^
   gap>

then you can see an arrow pointing to the expected position.

        Sergei
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