Dr. Cydr

Dr. Cydr is a reknownd mathmatician and was commisioned by the The Leauge of Abstraction  to describe the patterns of heartless and Nobodys mathmaticaly, he is one of the leading scientists in the department of Abstract anatomy and ecology.

the Heartless Respawn Equation
$$T=M(-D/L)$$

where T= the time in days taken between the heartless "death" and "reformation" M= the heartless's mass and -D/L is equal to the Ratio of Darkness and light in the subjects heart mesured in Globs

A glob is a unit used to mesure Darkness and light, it is equal to the minimum ammount of darkness nessessary to form a glob of pure darkness, hence the name, this is defined as the weight of the smallest ever created glob wich is kept inside of a vault in his labrotory and weghies aproximatly 2.675 Kg. and since light is the opposite of Darkness than a negative glob can be used to mesure the ammount of light.

Summouning Ansem
using this equation they were able to make a rough estimate of when ansem would reappear, and they need to capture castle oblivion, the location of his recreation before that time.