### Beskrivelse

Probabilistic Decision Graphs (PDGs) combine elements of probabilistic graphical

models and ordered binary decision diagrams (OBDDs). PDGs were first

proposed by M. Bozga and O. Maler in the context of probabilistic verification.

We have introduced a slightly generalized version of PDGs, and investigated

their properties from a reasoning under uncertainty point of view. Special

focus of this work is a comparison with Bayesian networks with regard to

efficiency of probabilistic inference, and with regard to the probabilistic independence

models that can be represented by the graphical structures in the

two frameworks. The results show that PDGs and Bayesian networks represent

different kinds of independence structures: whereas independence structures encoded

by Bayesian networks are given in terms of subsets of random variables,

the independence structures encoded by PDGs are given in terms of partitions

of the state space. For probability distributions exhibiting the latter type of

independence patterns, one can obtain significantly more efficient representations

(with regard to complexity of probabilistic inference) with PDGs than

with Bayesian networks.

We also have developed and implemented a learning algorithm for PDGs. We have conducted experiments in which both PDG and Bayesian network

models were learned from real-life data sets. Goal of the experiments was to

determine whether for some types of data the learning algorithms for the two

frameworks would produce models with significantly different inference complexity.

Somewhat surprisingly, the results showed that the learned models in the

two representation languages exhibited quite similar complexity characteristics.

models and ordered binary decision diagrams (OBDDs). PDGs were first

proposed by M. Bozga and O. Maler in the context of probabilistic verification.

We have introduced a slightly generalized version of PDGs, and investigated

their properties from a reasoning under uncertainty point of view. Special

focus of this work is a comparison with Bayesian networks with regard to

efficiency of probabilistic inference, and with regard to the probabilistic independence

models that can be represented by the graphical structures in the

two frameworks. The results show that PDGs and Bayesian networks represent

different kinds of independence structures: whereas independence structures encoded

by Bayesian networks are given in terms of subsets of random variables,

the independence structures encoded by PDGs are given in terms of partitions

of the state space. For probability distributions exhibiting the latter type of

independence patterns, one can obtain significantly more efficient representations

(with regard to complexity of probabilistic inference) with PDGs than

with Bayesian networks.

We also have developed and implemented a learning algorithm for PDGs. We have conducted experiments in which both PDG and Bayesian network

models were learned from real-life data sets. Goal of the experiments was to

determine whether for some types of data the learning algorithms for the two

frameworks would produce models with significantly different inference complexity.

Somewhat surprisingly, the results showed that the learned models in the

two representation languages exhibited quite similar complexity characteristics.

Status | Igangværende |
---|---|

Effektiv start/slut dato | 19/05/2010 → … |

### Finansiering

- <ingen navn>

### Fingerprint

Bayesian networks

Learning algorithms

Binary decision diagrams

Set theory

Random variables

Probability distributions

Experiments