Logic puzzle might be present in lieu of a grid in a puzzle about the location of different shops. Logic puzzle A logic puzzle is a puzzle deriving from the mathematics field of deduction. The logic puzzle was first produced by Charles Lutwidge Dodgson, who is better known under his pen name Lewis Carroll, the author of "Alice's Adventures in Wonderland". In his book "The Game of Logic" he introduced a game to solve problems such as confirming the conclusion "Some greyhounds are not fat" from the statements "No fat creatures run well" and "Some greyhounds run well". Puzzles like this, where
Logical biconditional Logical biconditional In logic and mathematics, the logical biconditional (sometimes known as the material biconditional) is the logical connective of two statements asserting "formula_1 if and only if formula_2", where formula_1 is an "antecedent" and formula_2 is a "consequent". This is often abbreviated "formula_1 iff formula_2". The operator is denoted using a doubleheaded arrow (↔), a prefixed E "E"pq"" (in Łukasiewicz notation or Bocheński notation), an equality sign (=), an equivalence sign (≡), or "EQV". It is logically equivalent to formula_7 and to formula_8 (or the XNOR (exclusive nor) boolean operator), meaning "both or neither". The only difference from material