l5a - UBC Computer Sciencenando/540b-2011/lectures/l5a.pdf · CPSC540 Nando de Freitas September,...

CPSC540

Nando de FreitasSeptember, 2011University of British Columbia

Discrete Probability and Bayesian Learning

Probability

Frequentist interpretation

Axiomatic interpretation

The axioms

Venn diagram:

OR and AND operations

Conditional probability

Conditional probability example

Marginalization

Marginalization example

Bayes rule

Learning and Bayesian inference

∑∈′

′′=

Hh

hphdp

hphdpdhp

)()|(

)()|()|(

d

h

Likelihood

Prior of “sheep” class

Posterior

“sheep”

Speech recognition P(words | sound) P(sound | words) P(words)

Final beliefs Likelihood of data Language modeleg mixture of Gaussians eg Markov model

Hidden Markov Model (HMM)

α

“Recognize speech” “Wreck a nice beach”

Definition of discrete r.v.s

Probability distributions

The CDF

Expectation

Bernoulli r.v.s and the indicator function

Maximum likelihood example

Maximum likelihood example

Bayesian learning

Beta prior

Example