title: 斯坦福-随机图模型-week1.1
tags: note
notebook: 6- 英文课程-9-Probabilistic Graphical Models 1: Representation
---
斯坦福-随机图模型-week1.1
练习
1。第 1 个问题
Factor product.
Let X,Y and Z be binary variables.
If ?1(X,Y) and ?2(Y,Z) are the factors shown below, compute the selected entries (marked by a ‘?‘) in the factor ψ(X,Y,Z)=?1(X,Y)??2(Y,Z), giving your answer according to the ordering of assignments to variables as shown below.
Separate each of the 3 entries of the factor with spaces, e.g., an answer of
0.1 0.2 0.3
means that ψ(1,1,1)=0.1, ψ(1,2,1)=0.2, and ψ(2,2,2)=0.3. Give your answers as exact decimals without any trailing zeroes.
0.16 0.45 0.6
在此输入您的回答
1
point
2。第 2 个问题
Factor reduction.
Let X,Z be binary variables, and let Y be a variable that takes on values 1, 2, or 3.
Now say we observe Y=1. If ?(X,Y,Z) is the factor shown below, compute the missing entries of the reduced factor ψ(X,Z) given that Y=1, giving your answer according to the ordering of assignments to variables as shown below.
As before, separate the 4 entries of the factor by spaces.
14 60 4 59
在此输入您的回答
第 3 个问题1
point
3。第 3 个问题
Properties of independent variables.
Assume that A and B are independent random variables. Which of the following options are always true? You may select 1 or more options.
P(B|A)=P(B)
P(A|B)=P(A)
P(A)+P(B)=1
P(A)=P(B)
1
point
4。第 4 个问题
Factor marginalization.
Let X,Z be binary variables, and let Y be a variable that takes on values 1, 2, or 3.
If ?(X,Y,Z) is the factor shown below, compute the entries of the factor
ψ(Y,Z)=∑X?(X,Y,Z),
giving your answer according to the ordering of assignments to variables as shown below.
Separate the 4 entries of the factor with spaces, and do not add any extra trailing or leading zeroes or decimal points.
在此输入您的回答
108 135 79 141