Which concept of the Indian logic system denotes circumstantial implication?

Circumstantial implication is denoted by Arthapatti.

It is the presumption of an unstated fact needed to explain a known one.

A fat man is known to be fat, yet is observed never to eat by day.

This is unintelligible unless one presumes that he eats by night.

Postulating that explaining circumstance is arthapatti.