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6.3 Interlinking Asian Resources in Chinese Alphabet: Han Edit Distance

China, Japan and Korea (CJK) are geographically close and have influenced each other language systems for thousand years. CJK share Han Chinese even though Japan and Korea have their own writing systems, and many currently used words in the three countries were derived from ancient Han Chinese. That means language resources existing in the three countries can be better matched and interlinked when the lineage is properly utilized. Therefore, a new linguistic similarity metric was developed to measure distances between commonly used Chinese letters among the three languages.

Han Edit Distance (HED) is a new similarity metric for Chinese, Japanese and Korean based on the Unihan database. The Unihan database covers more than 45,000 codes and contains mapping data to allow conversion to and from other coded character sets and additional information to help implement support for the various languages that use the Han ideographic script. As the Unihan database provides a variety of information associated with Han Chinese, HED measures similarities between two words by using this information.

As Han Chinese has been used in many Asian countries for a long period of time, Han characters are pronounced differently, and some of the shapes have changed over time in different regions. Reading category in the Unihan database shows the pronunciation of the same unified ideographs in Mandarin, Cantonese, Tang-dynasty Chinese, Japanese, Sino-Japanese, Korean and Vietnamese. The Variants category includes a variety of relationships with Han Chinese that can be used for interlinking. In Han Edit Distance, each piece of information about Han Chinese characters was classified into Reading and Semantic categories. That is, kMandarin, kJapaneseOn, kJapaneseKun, kKorean and kHangul are classified into the Reading category, and kSemanticVariant, kCompatibilityVariant, kSimplifiedVariant, kRSUnicode and kTotalStroke are classified into the Semantic category.

Figure 4 shows how HED is measured: it calculates Reading and Semantic distances using each category, sums the total distance, and normalizes the distance. The number of matching properties from the Reading category is the distance between two characters. Therefore, the maximum reading distance is 5 because Reading category has 5 properties. Semantic distance is calculated by comparing 3 semantic properties (semantic, compatibility, simplified variant). If any of the three matches, the two characters are believed to have a semantic relationship. If no match exists, then a semantic distance is calculated by counting radical strokes. That is, the number of total strokes of two characters when the

Fig. 4. Detailed process of Han Edit Distance algorithm

family root is the same becomes the distance. We defined 30 to be the maximum number of total strokes, even though the total number of strokes is larger than 30, but the number of Chinese characters that have more than 30 strokes is rare (about 0.23 %) in the Unihan database.

As Han Chinese words can be composed of one or more characters, we performed two types of experiments to compare with Levenshtein distance by using commonly used Han Chinese characters (1,936 pairs) and by using Han Chinese words (618 pairs). The F-measure scores of both experiments show better performance, specially as high as 23 % for Han Chinese words. From the experiment, the HED method shows performance improvements in comparison with Levenshtein distance for Han characters commonly used in Chinese, Japanese and Korean.

6.4 Asian Data Fusion Assistant

Integrating multilingual resources to derive new or unified values has not shown the full potential in the context of Linked Data partly because of language barriers. Asian Fusion Assistant, an extension of Sieve, aims at facilitating the fusion process by adding translation functionality from one Asian language to another. While machine translation systems pursue full automatic translation without human intervention by using a large bilingual corpora, building a machine translation system for each pairs of languages is hard to achieve. Therefore, we adopted a translation memory approach for two reasons. First, existing human translations can be fully utilized. Second, not every part of RDF triples ought to be translated, but only plain literals that have language tags.

A translation memory system provides similar translation pairs upon translator's requests and stores new translation pairs produced by human translators. Wikipedia (and hence, DBpedia) texts with inter-language links for many languages is a valuable source of translation memories. Therefore, parallel text pairs were collected from Korean, English, Chinese and Japanese DBpedia and stored separately. Although RDF triple translation follows the architecture of translation memory systems, one major difference is that human translators are substituted with (free) internet translation services. The advantages of using the Internet translation API services (e.g. Microsoft Bing) are that they usually support many language pairs and because the concerns about translation quality are reduced as texts to be translated are not sentences but nouns or noun phrases.

Fig. 5. Asian fusion process

Asian resource fusion process consists of 4 steps: translation, encoding, quality assessment/conflict resolution and decoding as shown at Fig. 5. Translation is only invoked when input triples contain plain literals with language tags. Encoder encodes multi-byte letters (e.g. Korean) into a stream of single-byte letters, and then Sieve performs quality assessment and conflict resolution to produce an integrated result. Finally, Decoder decodes all encoded strings into the original language again. We expect that translation memory systems can be globally interconnected and can boost the multilingual data fusion.

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