In 1988, Dong ZhenDong proposed several important principles for building a knowledge base (http://www.keenage.com/). He suggested that all concepts should be defined by a closed set of primitives and features which is different to, organizing concepts into synonym sets, as is the case in WordNet. This approach provides richer information for natural language processing and is more flexible for generating a new concept. Dong used over 2,000 primitives and over 200 hundred Event-role and Features to describe general concepts and map the relations among them. The following is an example.

In 2003, the Sinica CKIP group and Professor Dong began a cooperative project to build a HowNet for traditional Chinese, called HowNet-Big5. We adopted the HowNet-based meaning representation mechanism to define the word meanings of over 70,000 lexical entries in the CKIP Chinese Lexical Knowledge Base. However, we had to make some changes to the HowNet definition structure to address the capabilities of semantic composition and decomposition properties of the model. We invented and added the description of Multi-level meaning representation and complex relation/relations? Instead of using primitives, basic concepts are used as the elements to define complex concepts. As a result, HowNet-Big5 evolved into a new knowledge representation model, called Extended-HowNet. For more details, please read the article " Extended-HowNet: multi-level concept definition and complex relation description" by Chen et al.

The advantages of Extended-HowNet are as follows:

1. Extended-HowNet represents concepts in more accurate way by not restricting the definition vocabulary to a closed set of primitives only, i.e., any well-defined concepts can be used to define a new concept.

 
2. It accords with human cognition models. Since complex concepts are defined by basic concepts, the definitions are easier to understand.
    
3. To reach a canonical representation, if a lexical concept is defined by different annotators, the different higher level definitions can be converted into same or similar primitives at the end.

 
4. The conversion of primitives into WordNet synsets makes the representation language independent.

 
5. The definitions in Extended-HowNet are designed for easy semantic composition, decomposition, and translation into natural language expressions.
    
6. Complex definitions are facilitated to define kinship relations, temporal and spatial concepts, comparative notions, etc.

1. Every primitive of HowNet has been connected to the WordNet synsets.

 
2. The taxonomy structures for semantic roles have benn constructed. Please see attached files: The semantic roles for nouns, The semantic roles for verbs, The semantic roles for relations.

 
3. A total of 55,912 words (including 60,482 concepts) in the CKIP Chinese Lexical Knowledge Base have been defined as being the Extended-HowNet format. For example