Hypergraph Format

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Revision as of 10:23, 8 November 2010 by Chrisq (talk | contribs)

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Overall goal

Make it easy to share packed representations across NLP applications. Therefore we want a spec that is primarily easy to use from a variety of different platforms and languages. A memory efficient and fast representation is also useful.

Serialization library options


JSON Description


  • Implementations in every language (often packaged with language).
  • Human readable
  • Already used in CDec for forest output


  • Space inefficient
  • Requires custom parser for speed

Protocol Buffers

Protocol Buffer Description

Implementation Sketch


  • Conversion to and from JSON (protobuf-json)
  • Very fast to read (particularly in C++ and Java, hopefully soon in python)
  • Very space efficient
  • Implementations in Java, C++ and Python; generates typed stubs in those languages


  • No implementations for Perl, C#, or other languages commonly used by NLP folks
  • Requires a separate library; adds an external dependency to spec
  • "It's really easy to get up to some of the data size limits that are in place to prevent malicious data from having the PB parser allocate too much memory". Some of the limits are described in the section describing SetTotalBytesLimit on this page.
  • "You typically have to create a full hypergraph protocol buffer object before you can serialize it, so you either have to use the PB data structures internally in your code or you have to copy your data structure. While doing this copy, you can end up with two copies of the forest in memory, which is bad for memory usage."

Variation of SLF (Standard Lattice Format)

SLF Specification


  • Blindingly fast.
  • Could be implemented to work lazy/streaming.


  • Requires a custom format
  • Probably need specialized language bindings.

Tiburon Format

Tiburon Specification