Introduction

The Oslo-Bergen Tagger is a morphosyntactic tagger for Norwegian bokmål and nynorsk. For general information about the tagger, visit its home page: http://www.tekstlab.uio.no/obt-ny/.

Using Docker

The easiest way to run the tagger is by using the Docker image found at https://hub.docker.com/r/textlab/obt. The following example pulls version 1.0 of the image from Docker Hub if necessary, mounts the host directory /tekstlab as /texts inside the Docker container and runs the tag-bm.sh command on the file test.txt in that directory (see 'Running the tagger' below for the different ways to run the tagger):

docker run -it --rm -v /tekstlab:/texts textlab/obt:1.0 ./tag-bm.sh /texts/test.txt

Installation and usage

If running the tagger as a Docker container is not an option, the tagger can be installed using the following instructions.

The tagger consists of three parts:

• A multitagger (tokenizer, morphological analyzer, and compund analyzer)
• A Constraint Grammar (CG) tagger
• A statistical tagger (currently only for bokmål)

The multitagger

The multitagger is written in Python and can be cloned from https://github.com/textlab/mtag:

git clone git://github.com/textlab/mtag.git

The Constraint Grammar tagger

1. Check out VISL CG-3 from the Github repository created by the University of Southern Denmark (https://github.com/GrammarSoft/cg3) and install it. The repository can be checked out anywhere on your machine since it will be installed into a central location such as /usr/local/bin. For some platforms, there are also ready-made binaries available. Installation instructions for various platforms can be found at http://beta.visl.sdu.dk/cg3/chunked/installation.html.

2. CG rules for morphological disambiguation of bokmål and nynorsk are found in the cg folder.

   bm_morf.cg and nn_morf.cg should be used when you only want to do CG tagging of bokmål and nynorsk, respectively. The CG tagger may leave some ambiguity, either because it is not confident enough to do complete disambiguation, or because there is genuine ambiguity in the material (such as nouns that can be analyzed as either masculine or feminine).

   bm_morf-prestat.cg should be used when you want to run statistical disambiguation after CG disambiguation in order to obtain completely disambiguated output (currently only available for bokmål). This is useful, for instance, for many language technology purposes. On the other hand, it may remove genuine ambiguity from the text.

The statistical tagger

Clone the OBT-Stat git repository from GitHub in the root folder of the distribution:

git clone git://github.com/textlab/OBT-Stat.git

Running the tagger

Shell scripts are included which will run the entire process: multitagging, CG disambiguation, and optionally statistical disambiguation (for bokmål).

CG and statistical disambiguation, bokmål:

./tag-bm.sh TEXTFILE > DISAMBIGUATED_OUTPUT_FILE

CG disambiguation only, bokmål:

./tag-nostat-bm.sh TEXTFILE > DISAMBIGUATED_OUTPUT_FILE

CG disambiguation only, nynorsk:

./tag-nostat-nn.sh TEXTFILE > DISAMBIGUATED_OUTPUT_FILE

Third-party software that uses the tagger

Clojure library by Aleksander Skjæveland Larsen
Python library by Mats Byrkjeland