Puzzle requiring the use of the process of logical deduction to solve. Logical puzzles do not admit of a standard procedure or generalized pattern for their solution and are usually solved by some trial-and-error method. This is not to say that the guessing is haphazard; on the contrary, the given facts suggest several hypotheses. These can be successively rejected if found inconsistent, until, by substitution and elimination, the solution is finally reached. The use of various techniques of logic may sometimes prove helpful, but in the last analysis, success depends largely upon that elusive capacity called ingenuity.