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Alphabetical logic (Posted on 2006-07-28) Difficulty: 3 of 5
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

  Submitted by Tristan    
Rating: 4.1250 (8 votes)
Solution: (Hide)
To solve this puzzle, you would most likely start with a standard grid matching up first and last names. The following grid contains the "obvious" clues (e.g. since Greg comes before Dirk, Greg cannot be be Sumner). Columns are last names, rows are first names.
   A D I L N S
D  x x   x x 
El x       x
Er x       x
G          x x
N            x
T  x   x     x
Perhaps the best way to go from here is to take a guess and check its logical consistency. For example, lets assume Austin is Nelson, and fill in the "obvious" clues that follow.
   A D I L N S
D  x x o x x x
El x x x o x x
Er x x x x x o
G  x o x x x x
N  o x x x x x
T  x x x x o x
This leads to a contradiction because Sumner is supposed to come before Lister, among other things. Therefore, Austin is not Nelson, and we can fill out the "obvious" clues that follow. To get the solution, it may be necessary to make more guesses in the same manner.
Dirk   Ives
Ellen  Sumner
Erik   Lister
Greg   Austin
Nelson Newton
Tony   Dunn
Erik, Mr. Lister guesses, must be his first name, but he's really not that sure.

The compulsive cryptographers among you may have noticed that the first letter of each last name when read down spells "island." What does it mean? Mr. Lister thinks it is a coincidence.

Comments: ( You must be logged in to post comments.)
  Subject Author Date
AnswerK Sengupta2009-03-06 06:19:50
Alpha logicChuck Hurst2006-08-21 16:05:12
SolutionAnother logical table solution (without the table)gregg tsujimoto2006-08-10 06:21:09
Solutionnames...briana2006-08-09 12:28:22
re: Analytical SolutionMagda2006-07-30 18:48:33
SolutionAnalytical SolutionSir Percivale2006-07-29 11:33:52
re(2): SolutionPenny2006-07-29 10:33:22
re: SolutionRichard2006-07-29 01:36:51
SolutionSolutionPenny2006-07-28 09:46:45
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