In philosophy and logic, the liar paradox or liar's paradox (pseudomenon in Ancient Greek), is the statement "this sentence is false". Trying to assign to this statement a classical binary truth value leads to a contradiction (see paradox).
If "this sentence is false" is true, then the sentence is false, which would in turn mean that it is actually true, but this would mean that it is false, and so on ad infinitum.
Similarly, if "this sentence is false" is false, then the sentence is true, which would in turn mean that it is actually false, but this would mean that it is true, and so on ...
Here is a quote from the wikipedia entry on semidirect products of groups:
There are also far-reaching generalisations in category theory. They show how to construct fibred categories from indexed categories. This is an abstract form of the outer semidirect product construction.
Do ...
