Fw: Re: Multiplying permutations
- To: mathgroup at smc.vnet.net
- Subject: [mg41855] Fw: Re: [mg41723] Multiplying permutations
- From: "Mihajlo Vanevic" <mvane at eunet.yu>
- Date: Sat, 7 Jun 2003 00:08:44 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Wolfgang,
I tried to send you a private e-mail,
but it didn't reach you...
So, this time, I'm going to post it to the MathGroup too :)
Mihajlo
************* THIS IS A FORWARD MESSAGE ****************
* At 2003-06-03, 15:13:55
* Mihajlo Vanevic, mvane at EUnet.yu wrote:
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>In[]:=
>Clear[CenterDot]
>
>In[]:=
>SetAttributes[CenterDot, {Flat, OneIdentity}]
>
>In[]:=
>p_·q_ := q[[p]];
>
>In[]:=
>{3, 1, 2}·{2, 1, 3}
>
>Out[]=
>{3, 2, 1}
>
>In[]:=
>({3, 1, 2}·{2, 1, 3})·{3, 2, 1}
>
>{3, 1, 2}·({2, 1, 3}·{3, 2, 1})
>
>{3, 1, 2}·{2, 1, 3}·{3, 2, 1}
>
>
>You can enter · symbol with Esc . Esc (on Windows)
>
>Regards,
> Mihajlo Vanevic
> mvane at EUnet.yu
> 2003-06-03
>
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>* At 2003-06-03, 07:13:00
>* Dr. Wolfgang Hintze, weh at snafu.de wrote:
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>>Is there a simple command in Mathematica to multiply two permutations,
>>i.e. to carry out one after the other?
>>
>>I looked at the packages DiscreteMath`Permutations` and
>>DiscreteMath`Combinatorica` but couldn't find it.
>>
>>Example
>>
>>p = {3,1,2} mapping: 1->3, 2->1, 3->2
>>q = {2,1,3} mapping: 1->2, 2->1, 3->3
>>p.q = mappings (p first, then q)
>> [1-p->3-q->3, 2-p->1-q->2, 3-p->2-q->1]
>>= {3,2,1}
>>
>>Any help appreciated
>>
>>Wolfgang
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