If X: Known substance; Y: New form of a known substance; P: New property or new use of a known…

Section 3(d) of the Patents Act, 1970 excludes "the mere discovery of a new form of a known substance which does not result in the enhancement of the known efficacy" (Y∩Cᶜ), the mere discovery of any new property or new use for a known substance (P), and the mere use of a known process, machine or apparatus (A) "unless such known process results in a new product or employs at least one new reactant".

A new form with enhanced efficacy (Y∩C), and a known process that employs a new reactant or yields a new product, therefore fall outside the exclusion. The other formulas reverse the patentable and non-patentable sets.