Komanamana Sankaranarayanan Subramonian Nambooripad, Indian mathematician (Puttumanor, Ernakulam District, Kerala State 06 April 1935 – Thiruvanathapuram, Kerala State 04 January 2020)

Characterised axiomatically the structure of the set of idempotents in a regular semigroup (1979)

Developed an alternative approach to describe the structure of regular semigroups

Developed the concept and terminology of a biordered set (1970s)

EPONYMY 

Nambooripad structure theorem for regular semigroups

Hartwig-Nambooripad partial order (1980)

Ehresmann-Schein-Nambooripad theorem