Hierarchical Name Entity Recognition

Traditional NER assume that each entity type is an independent class.

However, they can have a hierarchical structure

Motivation

Genia Corpus

All models are based on MEMM classifier Model 1

◦ Just take the ancestor types to be features Model 2

◦ Train a classifier at each level◦ Do verterbi on paths in the tree

Models

Every node in the tree has a local weight and global weight

Global weight is for classification. ◦ The sum of the local weights from the root to the

node Example

Model 3

Results

Thanks David and Mihai for insightful discussions

Thanks instructors for excellent courses Thanks TAs for hard work.

Acknowledgement