let M be non empty-yielding Conditional_Probability Matrix of REAL ; :: thesis: for p being FinSequence of REAL holds
( p = Entropy_of_Cond_Prob M iff ( len p = len M & ( for k being Element of NAT st k in dom p holds
p . k = - (Sum ((Infor_FinSeq_of M) . k)) ) ) )

let p be FinSequence of REAL ; :: thesis: ( p = Entropy_of_Cond_Prob M iff ( len p = len M & ( for k being Element of NAT st k in dom p holds
p . k = - (Sum ((Infor_FinSeq_of M) . k)) ) ) )

A1: ( len (Infor_FinSeq_of M) = len M & width (Infor_FinSeq_of M) = width M ) by Def8;
then A2: ( dom (Infor_FinSeq_of M) = dom M & Seg (width (Infor_FinSeq_of M)) = Seg (width M) ) by FINSEQ_3:31;
hereby :: thesis: ( len p = len M & ( for k being Element of NAT st k in dom p holds
p . k = - (Sum ((Infor_FinSeq_of M) . k)) ) implies p = Entropy_of_Cond_Prob M )
assume A3: p = Entropy_of_Cond_Prob M ; :: thesis: ( len p = len M & ( for k being Element of NAT st k in dom p holds
p . k = - (Sum ((Infor_FinSeq_of M) . k)) ) )

then A4: ( len p = len M & ( for k being Element of NAT st k in dom p holds
p . k = Entropy (Line M,k) ) ) by Def11;
then A5: dom p = dom M by FINSEQ_3:31;
now
let k be Element of NAT ; :: thesis: ( k in dom p implies p . k = - (Sum ((Infor_FinSeq_of M) . k)) )
assume A6: k in dom p ; :: thesis: p . k = - (Sum ((Infor_FinSeq_of M) . k))
A7: k in dom (Infor_FinSeq_of M) by A1, A4, A6, FINSEQ_3:31;
thus p . k = Entropy (Line M,k) by A3, A6, Def11
.= - (Sum (Line (Infor_FinSeq_of M),k)) by A5, A6, Th53
.= - (Sum ((Infor_FinSeq_of M) . k)) by A7, MATRIX_2:18 ; :: thesis: verum
end;
hence ( len p = len M & ( for k being Element of NAT st k in dom p holds
p . k = - (Sum ((Infor_FinSeq_of M) . k)) ) ) by A3, Def11; :: thesis: verum
end;
assume A8: ( len p = len M & ( for k being Element of NAT st k in dom p holds
p . k = - (Sum ((Infor_FinSeq_of M) . k)) ) ) ; :: thesis: p = Entropy_of_Cond_Prob M
then A9: dom p = dom M by FINSEQ_3:31;
now
let k be Element of NAT ; :: thesis: ( k in dom p implies p . k = Entropy (Line M,k) )
assume A10: k in dom p ; :: thesis: p . k = Entropy (Line M,k)
thus p . k = - (Sum ((Infor_FinSeq_of M) . k)) by A8, A10
.= - (Sum (Line (Infor_FinSeq_of M),k)) by A2, A9, A10, MATRIX_2:18
.= Entropy (Line M,k) by A9, A10, Th53 ; :: thesis: verum
end;
hence p = Entropy_of_Cond_Prob M by A8, Def11; :: thesis: verum