let Omega be non empty set ; :: thesis: for Sigma being SigmaField of Omega
for f, g being Real-Valued-Random-Variable of Sigma holds f - g is Real-Valued-Random-Variable of Sigma

let Sigma be SigmaField of Omega; :: thesis: for f, g being Real-Valued-Random-Variable of Sigma holds f - g is Real-Valued-Random-Variable of Sigma
let f, g be Real-Valued-Random-Variable of Sigma; :: thesis: f - g is Real-Valued-Random-Variable of Sigma
set Y = [#] Sigma;
dom g = [#] Sigma by FUNCT_2:def 1;
then f - g is [#] Sigma -measurable by MESFUNC6:29;
hence f - g is Real-Valued-Random-Variable of Sigma ; :: thesis: verum