Adequality
= Adequality
A procedure associated with <Pierre de Fermat> for <extrema> and <tangents>. Compare expressions at $a$ and $a+e$, remove common terms, divide by a remaining power of $e$, and suppress terms still containing $e$. Its interpretation must be distinguished from ordinary equality at finite $e$ and from a modern <limit> definition.<Fermat's rule for maxima and minima by the Garden of Archimedes>{ref}