TITLE: Special name for two variables that sum to one?
QUESTION [5 upvotes]: I'm curious if there is any special name for the variables in the following function:
$\alpha+\beta=1$,
such that each can be determined by subtracting 1 from the other. Sort of like saying $\alpha$ is the 'reciprocal' of $\beta$ ...but through subtraction by 1 instead of division by 1.

REPLY [4 votes]: We might say that $\beta$ is the complement of $\alpha$ in $1$ and vice versa.