## Issue with PathGraph

10

2

Bug introduced in 8.0.0 and fixed in 9.0.0

I am having a strange issue with PathGraph. Executing

PathGraph[{a, b, c}]


or PathGraph[{1,2,3}], etc., returns a path-graph with three vertices as expected. However, executing:

In[10]:= PathGraph[{v1, v2, v3}]
Out[10]= PathGraph[{v1, v2, v3}]


That is, it stays unevaluated instead of returning the Graph object. I tried several variations and apparently the issue occurs whenever v2 is among the vertices. That is all of PathGraph[{a1, v2, a3}], PathGraph[{v2, x}], PathGraph[{1, 2, v2, x}], etc. remain unevaluated after execution.

I tried this on two computers, both with clean Kernels (with no definitions made or packages loaded, etc.).

Mathematica version: 8.0.0.0

Can anyone reproduce this? Is this a bug?

1I can repro this one. Awful. – Dr. belisarius – 2012-06-03T04:59:09.540

Me too. Also, neither of these work either: PathGraph[{j, k, l}]; PathGraph[{v, w, x}] – Jagra – 2012-06-03T05:07:09.170

2

Daniel Lichtblau has, on several occasions, commented/answered saying that such bugs are often caused by some internal variable sorting or issues with hashing. There is no way to predict which ones will fail, but they fix them as they find them. Here's a rather nasty bug on versions 7 and below (fixed in 8 onwards) that's somewhat related. I'd suggest emailing to support@wolfram.com

– rm -rf – 2012-06-03T05:21:09.230

1I emailed them. Waiting for reply. – becko – 2012-06-03T16:10:26.683

@becko Please share the reply when you get one. – Szabolcs – 2012-06-04T07:19:17.777

@Szabolcs Sure. See the answer. – becko – 2012-06-04T17:07:37.233

6

This is definitely a bug. I emailed Wolfram support and got the following reply:

Hello,