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信息論與編碼理論第二章****題答案(王育民)
LT
=
=()+()=(5/8)log5-1≈
(b) 由于P(Z=1/ Y=1)=1, 所以 P(Y=1,Z=1/X=1)= P(Y=1/X=1)=
P(Y=1,Z=1/X=0)= P(Y=1/X=0)=
那么P(Z=1/X=1)= P(Z=1,Y=1/X=1)+ P(Z=1,Y=0/X=1)=+ P(Z=1/Y=0,X=1)P(Y=0/X=1)=+*=
P(Z=1/X=0)= P(Z=1,Y=1/X=0)+ P(Z=1,Y=0/X=0)=+P(Z=1/Y=0,X=0)P(Y=0/X=0)=+*=
P(Z=1,X=1)= P(Z=1/X=1)*P(X=1)=*=
P(Z=1,X=0)= P(Z=1/X=0)*P(X=0)= *=
P(Z=1) = P(Z=1,X=1)+ P(Z=1,X=0) =
P(X=0/Z=1)==69/104
P(X=1/Z=1)=35/104
I(X ;Z=1)=
=
=(69/104)log(23/26)+( 35/104)log(35/26) ≈
(c)H(X)=*log(1/)+*log(1/)=2-(3/4)log3=
H(Y/X)=-P(X=1,Y=1)logP(Y=1/X=1) -P(X=1,Y=0)logP(Y=0/X=1)
-P(X=0,Y=1)logP(Y=1/X=0) -P(X=0,Y=0)logP(Y=0/X=0)
=-*-*-*-*
=1/4+(3/40)log10-(27/40)log(9/10)≈
H(XY)=H(X)+H(Y/X)=9/4+(3/4)log10-(21/10)log3=
P(X=0,Y=0,Z=0)= P(Z=0 / X=0, Y=0)* P( X=0, Y=0)=(1-)*(-)=
P(X=0,Y=0,Z=1)= P(Z=1 / X=0, Y=0)* P( X=0, Y=0)=*=
P(X=1,Y=0,Z=1)= P(Z=1/ X=1,Y=0)* P(X=1,Y=0)=*(-)=
P(X=1,Y=0,Z=0)= P(Z=0/ X=1,Y=0)* P(X=1,Y=0)=*=
P(X=1,Y=1,Z=1)=P(X=1,Z=1)- P(X=1,Y=0,Z=1)=-=
P(X=1,Y=1,Z=0)=0
P(X=0,Y=1,Z=0)=0
P(X=0,Y=1,Z=1)= P(X=0,Z=1)- P(X=0,Y=0,Z=1)= -=
H(XYZ)=-*-*-*-*-*-*=(113/100)+(31/20)log10-(129/50)log3=+++++= bit
H(Z/XY)=H(XYZ)-H(XY)= -28/25+(4/5)log10-12/ =
解:
A信息論與編碼理論第二版答案信息論與編碼理論第二版答案,B,C分別表示三個篩子擲的點數。
X=A, Y=A+B, Z=A+B+C
由于P(A+B+C/ A+B)=P(C/A+B)=P(C)
所以H(Z/Y)=H(A+B+C/ A+B)=H(C)=log6 =
H(X/Y)= H(A/Y)
Y
組合數目
組合情況(A+B)
P(A=a/Y=y)
12
1
6+6
1
11
2
5+6,6+5
1/2
10
3
4+6,5+5,6+4
1/3