Abstract: Conditional random fields, which model the distribution of a multivariate response
conditioned on a set of covariates using undirected graphs, are widely used in a
variety of multivariate prediction applications. Popular instances of this class of
models, such as categorical-discrete CRFs, Ising CRFs, and conditional Gaussian
based CRFs, are not well suited to the varied types of response variables in
many applications, including count-valued responses. We thus introduce a novel
subclass of CRFs, derived by imposing node-wise conditional distributions of response
variables conditioned on the rest of the responses and the covariates as
arising from univariate exponential families. This allows us to derive novel multivariate
CRFs given any univariate exponential distribution, including the Poisson,
negative binomial, and exponential distributions. Also in particular, it addresses
the common CRF problem of specifying “feature” functions determining the interactions
between response variables and covariates. We develop a class of tractable
penalized M-estimators to learn these CRF distributions from data, as well as a
unified sparsistency analysis for this general class of CRFs showing exact structure
recovery can be achieved with high probability.
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Citation
- Conditional Random Fields via Univariate Exponential Families (pdf, software)
E. Yang, P. Ravikumar, G. Allen, Z. Liu.
In Neural Information Processing Systems (NIPS), December 2013.
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