This document describes the morphology module of the Lexicon Model for Ontologies as a result of the work of the Ontology Lexicon community group (OntoLex-Morph). The module is targeted at the representation of linguistic morphology in dictionaries and and other linguistic resources, as well as the formalization of rules for word formation and inflection as employed in computational morphology and grammatical appendices as frequently provided as part of bilingual dictionaries.

This module operates in combination with the lemon core module and extends it with support for two distinct views on linguistic morphology:

1. OntoLex-Morph allows to enrich lexical entries and individual forms with information about the morphological units that they consist of (descriptive morphology). This improves the capability of OntoLex-Lemon to encode, preserve and document the structure of morphologically complex forms or lexical entries.

2. OntoLex-Morph allows to formalize morphological rules that can be used to produce complex lexical entries and inflected forms from their component morphs, resp., their base forms (generative morphology). This allows to extend OntoLex-Lemon resources with a framework that describes how to produce and analyze complex lexical entries or inflected forms.

OntoLex-Morph has been designed with the premise to make OntoLex-lemon applicable to morphologically rich languages of any type, supporting both fusional and agglutinating morphology, and thereby contributing to a truly multilingual web.

This document is an official report of the OntoLex community group. It does not represent the view of single individuals but reflects the consensus and agreement reached as part of the regular group discussions. The report should be regarded as the official specification of lemon.

If you wish to make comments regarding this document, please send them to public-ontolex@w3.org (subscribe, archives).

Introduction

Morphology is a vital and, in many languages, very sophisticated part of language, and as such it has been an important part of the work of lexicographers. In the traditional print form, morphological information is provided in brief abbreviated terms that can only be deciphered with significant knowledge of the language, however with the transformation of the dictionary to an electronic resource a re-imagining of the morphology information in a dictionary is certainly due.

The morphology module aims at fulfilling two modelling purposes:

1. Stating elements that are involved in the decomposition of lexical entries and forms.

• Morphological decomposition on the lexical entry level.
  scope: The kind of elements of which a lexical entry can consist should be as non-restrictive as possible. I.e. The decomposition of lexical entries encompass lexical entries, components, derivational affixes, inflectional affixes, stems, roots and zero morphs. However, a lexical entry can NEVER be composed of a form!

• Morphological decomposition on the form level.
  scope: Elements of which a form can consist include roots, stems, inflectional affixes and zero morphs.

2. Enabling the representation of building patterns that are involved in the formation of lexical entries and forms.

• Representation of decompositional building patterns for lexical entries.
• Representation of decompositional building patterns for forms.

A fine-grained description of phonological and morphophonological processes that are involved in any kind of stem or word formation on the phoneme level is excluded and not representable with this Morphology Module. Only the elements between the lexical entry and the morph levels will be covered. It is possible, however, that such information may be addressed in future OntoLex modules.

The OntoLex-Morph module aims to be adequate for both traditional dictionary content (which contains only abbreviated information about morphological rules and paradigms, often organized in appendices) and structured computational data (morphological dictionaries) as used in Language Technology, with the goal of making resources from one community more accessible to the other.

Morphological Segments

Morphological Rules

Inflection

It may contain metadata information about this type of declension.

In the case of fusional morphology — languages like Greek, Latin or English — there is usually only one morph attached to a form that carries information about inflection. The situation is different for languages with agglutination, where each inflectional value is represented by its own morph. In order to represent this, the model has another class.

In order to set the order of morphs and also simplify the process of form generation, the property morph:next points from one InflectionSlot to the next.

Inflection Rules

The example below illustrates the modelling of inflection classes and rules for the generation of the genitive singular of lupus in Latin.

In a fusional language like Latin, there is no need to have different inflection slots: a single inflection rule (specific for the inflection class to which the lexical entry is assigned) allows for the generation of the genitive singular form as follows:

On the other hand, in an agglutinative language like Turkish, it is useful to define separate inflection slots for each morphosyntactic feature, and separate inflection rules for each inflection slot, as illustrated in the example below.

When a software compatible with the specifications runs on this data to generate forms of the entry :adam, it first extracts all the rules associated with the corresponding morphological pattern, namely sg_rule, pl_rule, and acc_rule. Next, it establishes the order of inflection slots mentioned in the rules (by looking for the slot that is not used as an object in a morph:next property).

Then, for the first inflection slot the correct form is chosen. If there is a morph:baseType specified in the rule, the corresponding form is chosen. Otherwise the canonical form is used. Finally, for each inflection slot, the transformation is applied. For the first slot the initial form is used, after that, the output of one transformation is used as an input for the next.

With each transformation, all the properties in the grammatical meaning associated with the rule are copied to a newly created grammatical meaning. After all the transformations have been applied, the form is created with the constructed grammatical meaning. The initial form and the morphs are added as objects for the morph:consistsOf statements.

It is also possible to create Morph elements during generation in case they are not present in the data.

In the case of the example above, the successive application of the two appropriate rules for accusative and plural formation – in the order established by the use of the morph:next property – allows for the generation of the accusative plural form as follows:

Base Types

For instance, for Latin verbs, in addition to the citation form, dictionaries also record “principal parts” – i.e., a set of forms from which the full paradigm of a lexeme can be inferred. E.g., the entry for rumpo in the Lewis and Short dictionary lists the forms: - rumpo, displaying the present stem rump-, from which other forms displaying the present stem can be inferred; - rupi, displaying the perfect stem rup-, from which other forms displaying the perfect stem can be inferred; - ruptum, displaying the so-called third stem rupt-, from which other forms displaying the third stem can be inferred;

This can be modelled with ontolex-Morph as follows:

Note that the inflection rules operating on the perfect and third stem are not only connected to the inflection class of rumpo, but also other ones, as they are valid across conjugations. By applying these rules, the following forms can be generated:

MP: as it has been shown that also derivation can be based a form different than the canonical one (e.g. Latin deverbal conversions from the Third Stem, like capio (Third Stem capt-) > capt-o), shouldn’t this hold also for WordFormationRule?

Word Formation