Mathematica 8 bug (related to Graph[])

[Szabolcs]

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]= <picture of a graph>

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?

Cheers,
Szabolcs

[Murray Eisenberg]

Same thing in 8.0.1, including getting a True result after copying the
Output[1] result.

I suggest you file a bug report at sugge...@wolfram.com. (Or using
the form at http://www.wolfram.com/support/contact/email/?topic=Feedback)

--
Murray Eisenberg mur...@math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower phone 413 549-1020 (H)
University of Massachusetts 413 545-2859 (W)
710 North Pleasant Street fax 413 545-1801
Amherst, MA 01003-9305