[r-t] Bobs only Erin Triples (was: Composition search)

[Ian Broster]

>> For example, if your path from root to node is ppppppb (because you have
>> already found that ppppppp is false (or actually, comes round and makes
>> any longer touch containing it false - awkward corner case!) then you do
>> not need to try (ever) the sequence ppppppp in your search space. You do
>> this by using the path ppppppb to prune direct the next recursive call.
>>
>> Sorry that's not explained very well! It was years ago I last coded
>> something like that.
>
> Actually, that's perfectly clear. The rotations point is interesting as  
> well, although checking if one path is a rotation of another might be  
> fairly expensive, especially as the paths get longer.

The point is that this algorithm automatically prunes all rotations "by  
construction" - there is no checking to do.




-- 
Ian Broster