A couple of weeks ago I noticed that Wolfram Alpha when asked for a uniquely 3-colorable graph [1] will hand you a graph that is not uniquely 3-colorable (which

A couple of weeks ago I noticed that Wolfram Alpha when asked for a uniquely 3-colorable graph [1] will hand you a graph that is not uniquely 3-colorable (which is easy to verify by evaluating the presented chromatic polynomial at 3 which should yield 6 for a uniquely 3-colorable graph but actually yields 12 indicating two possible 3-colorings). If you have a look at the Wolfram MathWorld article »Uniquely k-Colorable Graph« [2] you see the same wrong graph with the following information. It is implemented in Mathematica as GraphData["UniquelyThreeColorableGraph"] and Uniquely3ColorableGraph in the Mathematica package Combinatorica` , in the latter case replacing the incorrect graph (from Harary 1994, cover and p. 139) present in earlier version. So this bugfix did not really fix the bug. I reported it using the feedback form and we will see if the third attempt will get it right. [1] http://www.wolframalpha.com/input/?i=Uniquely3ColorableGraph http://www.wolframalpha.com/input/?i=Uniquely3ColorableGraph [2] http://mathworld.wolfram.com/Uniquelyk-ColorableGraph.html http://mathworld.wolfram.com/Uniquelyk-ColorableGraph.html