## April 1, 2005

## March 31, 2005

A Horn clause is restricted to have at most one positive literal. They are typically written as an implication statement which can be converted to a disjunctive clause: Horn clauses are an interesting restriction because they allow efficient resolution and...

Posted 5:46 PM -
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## November 12, 2004

## November 11, 2004

Jeff Bilmes makes an excellent point about distributions and talking about them correctly. In particular: An exponential distribution is a continous distribution. A geometric distribution is the discrete version. A gamma distribution is a continuous distribution. A negative binomial distribution...

Posted 5:08 PM -
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## October 20, 2004

There is a progression of sophistication in parameter estimation which goes as follows, from less sophisticated to more sophisticate: Maximum Likelihood: This is a point estimate of a parameter which defines an unobservable distribution. It is obtained by choosing the...

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## October 19, 2004

## July 16, 2004

From Decision-Theoretic Planning: Structural Assumptions and Computational Leverage: A classical STRIPS operator is described by a precondition and a set of effects. The former identifies the set of states in which the action can be executed, and the latter...

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A directed graphical model can be converted to an undirected graphical model through a process called moralization. Graphically, moralization is accomplished by creating an undirected clique for every node in the directed graph and it's parents. A directed graph...

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Belief propagation is an algorithm for efficiently calculating the probability of a variable in a graphical model given some evidence. This requires marginalizing out all the other variables in the graph. The naive approach to marginalization would lead to...

Posted 12:38 PM -
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From Policy Recognition in the Abstract Hidden Markov Model: Rao-Blackwellisation is a general technique for improving the accuracy of sampling methods by analytically marginalizing some variables and only sampling the remainder. In its simplest form, consider the problem of...

Posted 12:10 PM -
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## July 15, 2004

It is known that exact inference in Bayesian Networks is NP-Hard with respect to the network size. Cooper, G.F. (1990). The computational complexity of probabilistic inference using Bayesian belief networks. Artificial Intelligence, 42, 393-405 Approximate Bayesian Network inference scales...

Posted 5:21 PM -
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