let A be non empty set ; :: thesis: for v being Element of Valuations_in A
for S being Element of CQC-Sub-WFF holds Val_S (v,S) = Val_S (v,(Sub_not S))
let v be Element of Valuations_in A; :: thesis: for S being Element of CQC-Sub-WFF holds Val_S (v,S) = Val_S (v,(Sub_not S))
let S be Element of CQC-Sub-WFF ; :: thesis: Val_S (v,S) = Val_S (v,(Sub_not S))
Sub_not S = [('not' (S `1)),(S `2)] by SUBSTUT1:def 20;
hence Val_S (v,S) = Val_S (v,(Sub_not S)) by MCART_1:7; :: thesis: verum