Re: Strange ReplaceRepeated

• To: mathgroup at smc.vnet.net
• Subject: [mg17079] Re: Strange ReplaceRepeated
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Sat, 17 Apr 1999 03:34:51 -0400
• Organization: Universitaet Leipzig
• References: <7f1dko\$kou@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Hi Arturas,

there *is* a '1' in your expression ! Look at
FullForm[Infinity]

In[16]:=
FullForm[Infinity]

Out[16]//FullForm=
DirectedInfinity[1]

you see the '1' ? That must cause a infinite loop, because every time
the DirectedInfinity[1] is found it is replaced by
DirectedInfinity[Infinity] that is DirectedInfinity[DirectedInfinity[1]]
...

Hope that helps
Jens

Arturas Acus wrote:
>
> Dear Group,
>
> Here are very strange rezults from
> RplaceRepeated.
>
> Input:
>
> tarp=List[
>     List[AuxVertex[List[List[i2],m2]],
>       CG[List[i1,m1],List[i2,m2],List[i3,F[m3]]],
>       WD[i1,List[List[m1],List[m2]],List[q0]]],
>     List[AuxVertex[List[List[i1],m1]],
>       CG[List[i1,m1],List[i2,m2],List[i3,F[m3]]],
>       WD[i1,List[List[m1],List[m2]],List[q0]]]]
> Now try this on Linux box:
>
> tarp//.{F[_]:>S[Infinity],_?NumberQ:>S[Infinity]}
>
> It rezults in infinite loop. Using TracePrint indicates, that
> somewhere integer "1" appears for which NumberQ gives True. But there
> isn't '1' at all in tarp! What is happening here?
>
>
> Arturas Acus

```

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