Which Doctors encountered who?

This is a very pretty diagram from A Little Further out of the Way.

The blogger notes;

UPDATE (well, I messed that up, didn’t I? Let’s just ignore that, shall we? Thank god I noticed first.)

And I suspect the problem is that he describes this as a Venn diagram. It certainly looks like a Venn diagram – but is it? Does it show a logical relationship between the elements?

We’re not saying that The Master overlapping with The Slitheen is a logical reference to Lady Cassandra but could there be a logical relationship between those three given which Doctors they’ve encountered? Here’s an other attempt at a Doctor Who Venn diagram which illustrates the logical connections.

Either way; hmm, purty colours.