Tuning Hierarchies in P rinceton W ord N et (2016)

Abstract: Many new wordnets in the world are constantly created and most take the original Princeton WordNet (PWN) as their starting point. This arguably central position imposes a responsibility on PWN to ensure that its structure is clean and consistent. To validate PWN hierarchical structures we propose the application of a system of test patterns. In this paper, we report on how to validate the PWN hierarchies using the system of test patterns. In sum, test patterns provide lexicographers with a very powerful tool, which we hope will be adopted by the global wordnet community.

## introduction and background many new wordnets in the world are constantly created and most take the original princeton wordnet (pwn) as their starting point. this arguably central position imposes a responsibility on pwn to ensure that its structure is clean and consistent. this is particularly true for hierarchical relations, which are the most frequently encoded relations and which form the backbone of the network. to validate pwn hierarchical structures we propose the application of a system of test patterns developed in @xcite . importantly, all instances returned by the test pattern system were manually validated by two members of the estonian wordnet (estwn) team @xcite . the results were encouraging, and we applied the algorithms to pwn. we propose that after a few iterations on pwn other wordnets apply the algorithm on their resources and, after a couple of iterations, compare their structures with that of pwn, which can serve as some kind of gold standard for wordnets. alternatively, the analysis is commercially available from the first author. in this paper we report on how to validate the pwn hierarchies using the system of test patterns. a test pattern is a description of a specific substructure in the wordnet hierarchy. the system of test patterns and the descriptions of all patterns are found in @xcite . this system consists of ten test patterns that all involve multiple inheritance, an important property that can point to different semantic inaccuracies going back to lexicographic errors. because they are semantic, every test pattern applies cross-lingually and sheds new light on wordnets by examining their hierarchies and helping to detect and correct possible errors. these patterns were used to validate the semantic hierarchies of estonian wordnet over four years @xcite @xcite and on ten versions. during this time, the structure of estonian wordnet changed significantly, as described in section 3. the aim of this paper is to show that the same specific substructures that have been found in estonian wordnet also exist in princeton wordnet. moreover, some experiments on princeton word-net confirm the promising benefits of test pattern application (section 4). therefore, we propose test patterns as a method for validation and tuning hierarchies in pwn and all other wordnets. this paper is structured as follows: section 2 provides an overview of the validation methods applied to the wordnet hierarchies. section 3 presents the results of using test patterns iteratively on estwn. section 4 demonstrates that the same pattern instances can be found in pwn as well as in other wordnets. some experiments are described. we close with a conclusion and proposals for future work. ## state of the art in validating the semantic hierarchies of wordnet to give a better understanding of the test patterns approach we provide a short overview of the validation methods applied on the semantic hierarchies of wordnet. @xcite argues that the methods can be divided into three groups based on two features, as shown in group of methods use of corpus data, lexical resources use the contents of a synset group i + + group ii -+ group iii -- ## a case study: applying test patterns to estonian wordnet since 2011, different types of test patterns have been developed and applied progressively to estwn. currently, ten test patterns exist. for every test pattern we implemented a program to find the relevant instances. four programs are implemented for semi-automatic application (closed subsets, closed subset with a root, the largest closed subset and connected roots) and six for automatic use (the test patterns shown in italics in as all instances of test patterns include multiple inheritance cases, the fourth column (multiple inheritance cases) demonstrates the influence of using test patterns most clearly. for example, a comparison between versions 66 and 70 shows that the number of cases has gone down about 32 times (97%). note that 118 hierarchies contain about 75% of shallow hierarchies where roots are connected to only one level of subordinates. according to @xcite , over ten versions of estwn the most popular correction operation has been removing the hypernymy and hyponymy relations -21,911 times. secondly, the lexical units in synsets were changed 5,344 times (including deleted and added lexical units). thirdly, 4,122 times hypernymy and hyponymy relations were replaced by another semantic relation, mainly by near synonymy and fuzzynymy. ## validating princeton wordnet substructures connected with multiple inheritances have been used to validate pwn. @xcite @xcite examined shortcuts; rings were suggested by @xcite , and @xcite ) examined dangling uplinks. there are also some examples of closed subsets in @xcite and one example of heart-shaped substructure in @xcite ). lohk gave an example of a connected roots case in his poster presentation at estonian applied lingvistics conference in tallinn in april 2013. next, we provide some examples of test pattern instances to grasp their structure and how they may help to discover specific incosistencies in pwn semantic hierarhies. the complete overview of test patterns has been given in the dissertation of the first author @xcite .