or more succinctly
As opposed to the Epimenides paradox, this is a true paradox: assuming that the statement is true, then it must be false; assuming it is false, then it must be true. No truth value can be consistently assigned to the statement.
The proof of Gödels Incompleteness Theorem essentially consists of a formally correct formulation of a variation of this paradox in the context of a sufficiently strong [axiomatic system]?.
To avoid having a sentence refer to its own truth value, one can also construct the paradox