in reply to Re^4: Random Derangement Of An Array (rotate)
in thread Random Derangement Of An Array

It's not bad to map letters in the clear text to the same letter in the cypher text - as long as it's not more often than the statistical average.

No, it isn't bad - it is just wrong. To quote wikipedia on cryptogram, "...each letter is replaced by a different letter." Perhaps you don't know anyone who likes to do these puzzles but they would be extremely upset if they found one of the letters mapped to itself.

Cheers - L~R