DOUBLET is a word game invented by Lewis
Carroll, the author of Alice in Wonderland. He is also a
mathematician whose real name is Charles L. Dodgson. The object of the game is to change a word into another word by successively changing only
one letter at the time to form a intermediate valid word. For example, the
following process changes the word BUS to HAT:
I hope that posterity will judge me kindly,
not only as to the things which I have explained, but also to those which
I have intentionally omitted so as to leave to others the pleasure of
discovery.