Mostly Harmless

The best of the Two Tribes problems - Part 2

Continued from here.

You point to one of the paths and say:

"If I were to ask you if this path leads to the village would you say pish?"

This solution follows the normal pattern for this type of problem - but the pish/tush confusion is a novel twist. In our hut in Devon none of us (I and my brothers) succeeded in arriving at this solution but I do remember working out why this still works even when you don't know whether pish means yes or no (Mr Gardner left that part as a teaser).

I remember sitting at a trestle table and making a little grid out of knives and forks. I labelled the columns and rows with other domestic items and then filled in the grid with the answers given by the native. Salt meant pish and pepper meant tush. The resulting pattern was as follows:

	Path goes to village	Path does NOT go to village
Pish means YES
Pish means NO

From this I could see that if the native answers pish then the road goes to the village - regardless of whether pish means yes or no. In the general case, if the native uses the same word in the answer that you used in the question then the path leads to the village.

I remember the dawning sense of triumph I got from from examining this boolean decoration. Mum was less impressed: "That doesn't quite count as setting the table..."

Posted at 12:45PM Apr 27, 2007 by John Alderson in Problem Solving  |  Comments[0]