We show that solving jigsaw puzzles requires Θ(n ) edge matching comparisons, making them as hard as their trivial upper bound. This result generalises to puzzles of all shapes, and is applicable to both pictorial and apictorial puzzles.

Sudoku is a number placement mathematical puzzle based on logic. The purpose of this paper is to discuss suitable models and algorithm to generate Sudoku puzzles of varying difficulty. It is generally recognized that hand-made puzzles are more enjoyable than those generated by computer. Our goal is to establish models to generate Sudoku puzzles of varying difficulty, which are as enjoyable as h...

Spam and Denial-of-Service (DoS) attacks are growing threats on the Internet. Cryptographic puzzles can be used to address the problem effectively. Additionally, the Trusted Puzzle Solver (TPS), which is similar to the Trusted Platform Module (TPM), is also proposed to help constructing crypto puzzles that may have some outstanding specialties in security and efficiency. Based on the analysis a...

Sudoku is a very simple and well-known puzzle that has achieved international popularity in the recent past. This paper addresses the problem of encoding Sudoku puzzles into conjunctive normal form (CNF), and subsequently solving them using polynomial-time propositional satisfiability (SAT) inference techniques. We introduce two straightforward SAT encodings for Sudoku: the minimal encoding and...

Cryptographic puzzles provide an elegant solution in combating denial of services attacks. In this paper we introduce the concept of chained cryptographic puzzle. We define two kinds of chained puzzle constructions: linearly chained puzzles and randomly chained puzzles. The first construction prove to be very useful in some scenarios, from which the more general is in which a client may choose ...