Transition-based Dependency Parsing with Rich Non-local Features

Yue Zhang , Joakim Nivre ACL2011

Motivation

improve the accuracy of traditional-based dependency parsers by considering even richer feature sets than those employed in previous systems.

the Transition-based Parsing Algorithm

typical transition-based parsing process: the input words are put into a quenue and partially built structures are organized by a stack. A set of shiftreduce actions are defined, which consume words from the quenue and build the output parse.

arc-eager system:

• shift: removes the front of the queue and pushes it into the top of the stack;
• Reduce: pops the top item off the stack;
• LeftArc: pops the top item off the stack and adds it as a modifier to the front of the queue;
• LeftArc: removes the front of the queue, pushes it into the stack and adds it as a modifier to the top of the stack.