# Combining pattern-based CRFs and weighted context-free grammars

We consider two models for the sequence labeling (tagging) problem. The first one is a {\em Pattern-Based Conditional Random Field }(\PB), in which the energy of a string (chain labeling) $x=x_1\ldots x_n\in D^n$ is a sum of terms over intervals $[i,j]$ where each term is non-zero only if the substring $x_i\ldots x_j$ equals a prespecified word $w\in \Lambda$... (read more)

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