Reasoning with Uncertainty Flashcards
What properties must a belief measure satisfy?
Unit measure s must be a sample in the space
Additivity: suppose S1 and S2 are disjoint subsets of the space. Then our belief that S E S1 U S2 is the sum of our belief that s E S1 and out belief that s E s2.
What is the probability of a proposition?
The strength of belief that the proposition will hold.
How to calculate conditional probability?
P(h | e) = P(h ^ e)/P(e)
Also posterior probabilty
What is the chain rule?
P(a ^ b) = P(a)P(b |a)
What is the law of total probability?
P(a) = P(a | b)P(b) + P(a | -b)P(-b)
What is a bayesian network inference problem?
Given a bayesian network, compute the probability p(x | ly) and P(-X | ly)
How to normalise a CPT?
g(X’) = G(X) / G(x) +g(-X)
What is the chain rule?
See slides for answer
What is local Markov property?
When all neighbours are independent of any other vertices
What is the naive method of computing probabilities?
- Restrict final variable out
- Multiple previous table by probability table for next elvel up
- Sum out other variable to get final variable
- normalise above table to get probabilities
What time complexity does Naive method run on?
O(r^n), where r is the number of rows in CPT.
What is the algorithm for variable elimination?
See slides
