The ‘presence‘, ‘absence’ and ‘both’,
Of the probans in similar instances,
Combined with those if dissimilar instances,
There are three combinations in each of three.
The top and the bottom are valid,
The two sides are contradictory.
The four corners are inconclusive through being too broad,
The centre in inconclusive through being too narrow.
– R. S. Y. Chi: ‘The Treatise on the The Wheel of Reasons by Acārya Dignāga in ‘Buddhist Formal Logic’, Part 1, 1961