What Mr. Lister lacks in memory, he makes up with logic skills. Seriously, he can't remember anything. Can you match the six first names (Dirk, Ellen, Erik, Greg, Nelson, and Tony) with the six last names (Austin, Dunn, Ives, Lister, Newton, Sumner)?

These few memories are all that remain of his enigmatic and perhaps dramatic past:

1. When listed in alphabetical order by last name,
a)Greg comes before Dirk
b)Nelson comes before Ellen
c)Tony comes before Erik

2. When listed in alphabetical order by first name,
a)Austin comes before Newton
b)Ives comes before Dunn
c)Sumner comes before Lister

I drew up this table to check of the combinations that

can be eliminated.

       A D I L N S

Dirk   x x - x x -

Ellen  x - - - X -

Eric   x X - - X -

Greg   - - - - X x

Nelson - - - - - x

Tony   x - x - - x

The small x's are because those names cannot come

first or last. The large X's are due to specific

clues.

Now setting Tony to Newton leads to a contradiction.

Setting Nelson to Newton leads to a unique solution.

Posted by Sir Percivale on 2006-07-29 11:33:52