       Re: Element test

• To: mathgroup at smc.vnet.net
• Subject: [mg61217] Re: Element test
• From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>
• Date: Thu, 13 Oct 2005 01:39:28 -0400 (EDT)
• Organization: Uni Leipzig
• References: <dii8pd\$9cq\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Hi,

what may MemberQ[] do ??
Element[] is for infinite/uncountable quantities.

Regards
Jens

"leigh pascoe" <leigh at cephb.fr> schrieb im
Newsbeitrag news:dii8pd\$9cq\$1 at smc.vnet.net...
| Dear Group,
|
| I have a defined a graph that is a function of
n, gr1[n], with n^2 +4
| vertices and 2n(n+1) edges.
|
| I would like to remove some edges from this
graph, corresponding to all
| edges leading to the vertices in the set
list[n]. Since Ma doesn't seem
| to have a PERL like Foreach construct, I tried
something like the following:
|
| In:=
| Do[If[Element[i,list],
|    ShowGraph[test=DeleteEdges[gr1,{{{i,j}}
,{ j,1,40}}],
|      VertexNumber\[Rule]True]],{i,1,40}]
|
| Unfortunately this doesn't work. The problem
(apart from possible syntax
| errors) seems to lie in the fact that
|
| Element[i, list] never evaluates to True. For
a specific example
| using the list {4,2,9,39,40},
|
| In:=
| Element[39,list]
| Out=
| 39\[Element]{4,2,9,39,40}
|
| whereas the similar statement
|
| In:=
| 149\[Element]Primes
| Out=
| True
|
| How can I delete the edges to the vertices in
list[n] from my graph?
|
| Thanks
|
| LP
|

```

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