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.
Here's a solution to a classical puzzle:
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