Equivariant formality in $K$-theory

Abstract: In this note we present an analogue of equivariant formality in $K$-theory and show that it is equivalent to equivariant formality \emph{`a la} Goresky-Kottwitz-MacPherson. We also apply this analogue to give alternative proofs of equivariant formality of conjugation action on compact Lie groups, left translation action on generalized flag manifolds, and compact Lie group actions with maximal rank isotropy subgroups.