Calculational solutions to logical puzzles

On these pages I'm slowly building up a collection of solutions to logical puzzles, written down as calculational proofs.

For all these solutions I use [some logical notations].

I've started with puzzles from two books by Raymond Smullyan. He is a logician, philosopher, and author of a.o.

By the way, if anybody knows how Raymond Smullyan can be contacted, please let me know.

Here's a solution to a classical puzzle:

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Changes to calc/calc-sols.html:

Sat Oct 30 12:38:39 MEST 2004  Marnix Klooster
  * Move from CVS to darcs: do not show the CVS date anymore.

Tue Feb  5 14:42:44 MET 2002  marnix
  * Added tlott-4-5 and tlott-7-1 (and made tlott.html and calc-sols.html m4-aware)

Fri Sep 14 19:29:43 MEST 2001  marnix
  * added a opposite-twins puzzle

Wed Sep  5 21:20:00 MEST 2001  marnix
  * Made explicit that last changed date is in GMT

Wed Sep  5 21:08:51 MEST 2001  marnix
  * Now 'last changed' is on its own line

Wed Sep  5 10:10:47 MEST 2001  marnix
  * Added date last changed

Wed Sep  5 08:50:24 MEST 2001  marnix
  * Initial revision