Axiom 1. [=measurement axiom (Observable, Measured value, Measurement, Probability)] The measurement of the observable O for the system S with the state ω is denoted by M C ( Ω ) ( O : = ( X , P ( X ) , G ) , S [ ω ] ) . An observer can obtain a measured value x ( X ) by the measurement M C ( Ω ) ( O , S [ ω ] ) . And the probability that a measured value x ( X ) obtained by the measurement M C ( Ω ) ( O , S [ ω ] ) is given by [G({x})](ω).