Relation Metadata

This is a directory that contains metadata about the relations in your graph. None of this is required for the PRA code to function, but if you want to restrict predictions based on relation ranges, or keep the code from cheating by using known inverses, you should specify the directory containing these files in the experiment specification. The directory generally has the following entries:

• category_instances/: A directory containing all of the instances of each category, one category per file (format is just one instance per line). This, in conjunction with a ranges.tsv file, is necessary for restricting the predictions that PRA makes.

• domains.tsv: A mapping from relations to the category corresponding to the relation’s domain. Currently unused. Format is [relation] \t [domain], where domain must have a corresponding file in category_instances/.

• ranges.tsv: A mapping from relations to the category corresponding to the relation’s range. Used to restrict PRA’s predictions. Format is [relation] \t [range], where range must have a corresponding file in category_instances/.

• inverses.tsv: A mapping from relations to their inverses. This is used for restricting the random walks. When training a PRA classifier to predict a relation, you need to “remove” the edges that correspond to the training data, so you don’t learn things that won’t be useful, and edges that correspond to the testing data, so you’re not cheating. If there are known inverses in the graph, we need to remove both the original edge and its inverse, when applicable.

Not really metadata, but these are produced by my code that generates these directories for NELL and Freebase, and they might be handy in some other parts of the code:

• labeled_edges.tsv: Contains all relation instances in the KB, each of which will correspond to a single edge in a PRA graph. This file is generally referenced in a relation set, when creating graphs, as described below.

• relations/: A directory containing all of the instances of each relation, one relation per file. This is used to simplify the process of cross validation, when a fixed training/testing set isn’t specified in a split directory (see below).

If you are using Freebase, you shouldn’t have to create these directories manually. There is a class in the PRA code base, graphs.FreebaseKbFilesCreator, that does this for you. You could also download the data files from my EMNLP 2014 paper, as it contains relation metadata for NELL and Freebase, though they are under the kb_files/ directory, instead of the relation_metadata/ directory. I didn’t include the NellKbFilesCreator in this repository, because it has too many dependencies on the NELL codebase - I would have had to copy too many files over. If you really want to create new relation metadata for a newer version of NELL than you can get from the data files in the EMNLP 2014 paper, talk to me.