Re: Mathematica 8 bug (related to Graph[])

*To*: mathgroup at smc.vnet.net*Subject*: [mg119972] Re: Mathematica 8 bug (related to Graph[])*From*: Szabolcs <szhorvat at gmail.com>*Date*: Sat, 2 Jul 2011 05:02:31 -0400 (EDT)*Reply-to*: comp.soft-sys.math.mathematica at googlegroups.com

On Saturday, March 19, 2011 11:19:10 AM UTC+1, Szabolcs wrote: > Dear MathGroup members, > > There appears to be another bug in graph processing functions: > > In[1]:= jj = Subgraph[Graph[{1, 2, 3, 4}, {3 -> 4}], {1, 2, 3}] > > Out[1]= > > > In[2]:= IsomorphicGraphQ[jj, Graph[{1, 2, 3}, {}]] > > Out[2]= False > > In[3]:= InputForm[jj] > > Out[3]//InputForm= > Graph[{1, 2, 3}, {}] > > Strangely, if I copy and paste the output from Out[1] into the > IsomorphicGraphQ[] function, then the problem doesn't manifest > itself! To reproduce it, evaluate the input exactly as shown above > (try in a new session). Generally, any action that pulls the graph- > expression through the front-end seems to "fix" the problem. > > Can you reproduce the bug in Mathematica 8.0.1? > A possible workaround to this is applying Uncompress@Compress to the corrupted graph before testing for isomorphism.