Two sets may also constitute a trilemma (mu-gsum) or a tetralemma (mu-bzhi).    From Wordnik.com.  [Relationships between Two Objects in General] Reference

The relationship between two sets is a tetralemma if there are four possibilities.    From Wordnik.com.  [Relationships between Two Objects in General] Reference

For instances of the positive tetralemma, all four statement types can or must be accepted, e.g.    From Wordnik.com.  [Contradiction] Reference

Thus, the set of types of unawareness and the set of types of grasping for true existence constitute a tetralemma (mu-bzhi).    From Wordnik.com.  [The Twelve Links of Dependent Arising ��� Day One: Unawareness] Reference

On the other hand, much more use is made of the negative tetralemma, in which all four of the statements in (9) can or must be rejected.    From Wordnik.com.  [Contradiction] Reference

Finally, in §5, the tetralemma of Buddhist logic is discussed within the context of gaps and gluts; it is argued that apparent violations of LNC in this tradition and others can in be attributed to either differing viewpoints of evaluation (as foreseen by Aristotle) or to intervening modal and epistemic operators.    From Wordnik.com.  [Contradiction] Reference

Outside the Western canon, the brunt of the battle over LNC has been largely borne by the Buddhists, particularly in the exposition by Nâgârjuna of the catuskoti or tetralemma (c.    From Wordnik.com.  [Contradiction] Reference