let R be finite Approximation_Space; for Y, Z, W being Subset of R st Z misses W holds
kappa (Y,W) <= kappa ((Y \ Z),W)
let Y, Z, W be Subset of R; ( Z misses W implies kappa (Y,W) <= kappa ((Y \ Z),W) )
assume A0:
Z misses W
; kappa (Y,W) <= kappa ((Y \ Z),W)