This final strategy is reserved for the most difficult of the diabolical and, occasionally, tough puzzles – when all else fails.
Think of the Sudoku puzzle as a maze. Gentle and moderate puzzles have a simple path straight through to the exit. Tough and diabolical puzzles may have “dead” ends which force you to try different routes. A tough puzzle is usually a more torturous version of a moderate Sudoku, but it may have one of these dead ends to cope with. Diabolical puzzles will have at least one dead end, and maybe more paths that you could follow before finding the number that leads to a logical exit. The way to navigate this maze can be found in classical mythology. The following story will help to illustrate this.
Ariadne’s Thread
Ariadne was the daughter of King Minos of Crete, who conquered the Athenian nation. An unfortunate intimacy between Ariadne’s mother and a bull resulted in the birth of the monster – half bull, half man – called the Minotaur. The Minotaur was banished to spend his days in the Labyrinth. King Minos, being something of a tyrant, called for tribute from Athens in the form of young men and women to be sacrificed to the Minotaur.
The young Athenian hero, Theseus, offered to accompany a group of the young unfortunates into the Labyrinth so that he could kill the Minotaur and save Athens from the cruel tribute. Ariadne fell in love with Theseus and, not wishing to see him lost in the labyrinth once he had dealt with her bovine half brother, she provided him with a means of escape. She gave him a silken thread. Theseus had simply to unwind it while he went through the labyrinth; should he come to a dead end he could rewind it to the point where he had made a choice of paths and continue his search using the alternative route. The scheme worked out beautifully. The minotaur was slain and Theseus found his way back out of the labyrinth. And Ariadne? Well, she got her ball of string back and became the moral of this story.
The tale of Ariadne should illustrate that the method of solving Sudoku puzzles using a “string” to bring you back to an alternative route when you find a dead end will work each and every time.
Continue to Chapter 10...
