let p be ProbFinS FinSequence of REAL ; for M being non empty-yielding Conditional_Probability Matrix of REAL st len p = len M holds
Entropy_of_Joint_Prob ((Vec2DiagMx p) * M) = (Entropy p) + (Sum (mlt p,(Entropy_of_Cond_Prob M)))
let M be non empty-yielding Conditional_Probability Matrix of REAL ; ( len p = len M implies Entropy_of_Joint_Prob ((Vec2DiagMx p) * M) = (Entropy p) + (Sum (mlt p,(Entropy_of_Cond_Prob M))) )
set M1 = (Vec2DiagMx p) * M;
A1:
p is Element of (len p) -tuples_on REAL
by FINSEQ_2:110;
assume A2:
len p = len M
; Entropy_of_Joint_Prob ((Vec2DiagMx p) * M) = (Entropy p) + (Sum (mlt p,(Entropy_of_Cond_Prob M)))
then reconsider M1 = (Vec2DiagMx p) * M as Joint_Probability Matrix of REAL by Th28;
len (LineSum (Infor_FinSeq_of M)) =
len (Infor_FinSeq_of M)
by MATRPROB:def 1
.=
len p
by A2, Def8
;
then A3:
LineSum (Infor_FinSeq_of M) is Element of (len p) -tuples_on REAL
by FINSEQ_2:110;
A4: (Entropy p) + (Sum (mlt p,(Entropy_of_Cond_Prob M))) =
(- (Sum (Infor_FinSeq_of p))) + (Sum (mlt p,(- (LineSum (Infor_FinSeq_of M)))))
by Th63
.=
(- (Sum (Infor_FinSeq_of p))) + (Sum (- (mlt p,(LineSum (Infor_FinSeq_of M)))))
by A1, A3, RVSUM_1:94
.=
(- (Sum (Infor_FinSeq_of p))) + (- (Sum (mlt p,(LineSum (Infor_FinSeq_of M)))))
by RVSUM_1:118
;
Entropy_of_Joint_Prob M1 =
- (Sum (Mx2FinS (Infor_FinSeq_of M1)))
by Th59
.=
- (SumAll (Infor_FinSeq_of M1))
by Th42
.=
- ((Sum (Infor_FinSeq_of p)) + (Sum (mlt p,(LineSum (Infor_FinSeq_of M)))))
by A2, Th64
.=
(- (Sum (Infor_FinSeq_of p))) - (Sum (mlt p,(LineSum (Infor_FinSeq_of M))))
;
hence
Entropy_of_Joint_Prob ((Vec2DiagMx p) * M) = (Entropy p) + (Sum (mlt p,(Entropy_of_Cond_Prob M)))
by A4; verum