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[42]:= | Do[If[Element[i,list[6]], | ShowGraph[test=DeleteEdges[gr1[6],{{{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[6]] never evaluates to True. For a specific example | using the list {4,2,9,39,40}, | | In[33]:= | Element[39,list[6]] | Out[33]= | 39\[Element]{4,2,9,39,40} | | whereas the similar statement | | In[27]:= | 149\[Element]Primes | Out[27]= | True | | How can I delete the edges to the vertices in list[n] from my graph? | | Thanks | | LP |