NP-Complete and PSPACE-Complete Puzzles
Each of the 24 puzzles below have all been shown to be NP-Complete (with the exception of Rush Hour, which is PSPACE-Complete).
Is Chess a PSPACE Problem?
Chess on an arbitrary size board (with suitably adjusted rules) is PSPACE complete, as are many games.
Chess and Complexity
It’s a common misconception that chess is NP-hard. Generalized chess may be NP-hard. Chess has an 8×8 board, generalized chess has an nxn board with many pieces. I reason that it’s not NP-complete; not because it’s easier than NP-complete problems but because it’s harder.
Origin of Chess
Chess was invented in India around the 8th century. Then it was known as chatrang, and changed over the centuries by the Arabs, Persians and then ultimately the medieval Europeans, who changed the pieces’ names and appearances to resemble the English court.
Deep Blue vs Garry Kasparov
Garry Kasparov In the final game of a six-game match, world chess champion Garry Kasparov triumphs over Deep Blue, IBM’s chess-playing computer, and wins the match, 4-2.
Chess Computers
Chess computers were first able to beat strong chess players in the late 1980s. Since that time, chess programs running on commercial hardware—more recently including mobile phones—have been able to defeat even the strongest human players.
P Cryptography
- P is the plain text space or clear text space,
- C is the cypher text space, and
- K is the key space.
Elements of P are referred to as plain text, and elements of C are referred to as cypher text. A cryptosystem is called symmetric (or private key) if d = e, or if d can at least be “easily” computed from e.