1. Concept Description Vectors and the 20 Questions Game Włodzisław Duch Tomasz Sarnatowicz Julian Szymański

2. Semantic Memory Permanent container for general knowledge

3. Hierarchical Model Collins & Quillian, 1969

4. Semantic network Collins & Loftus, 1975

5. Semantic Memory

6. Semantic Space All the concepts and keywords create a semantic matrix

7. Concept Description Vectors CDV – a vector of properties describing a single concept Most of elements are 0’s – sparse vector

8. Data Sources I Machine readable dictionaries and ontologies: –Wordnet –ConceptNet –Sumo/Milo ontology

9. Data Sources II Dictionaries data retrieval –On-line sources Merriam Webster Wordnet (gloss) MSN Encarta –Approach Word morphing Phrases extraction (with POS tagger) Statistical analysis

10. Data access Binary dictionary search 2 20 = 1048576 Binary search – not acceptable in complex semantical applications Narrowing concept space by subsequent queries

11. 20 Questions Game Algorithm p(keyword=v i ) is fraction of concepts for which the keyword has value v i Candidate concepts O(A) are selected according to: O(A) = {i; |CDV i -A| is minimal} where CDV i is a vector for concept i and A is a partial vector of retrieved answers

12. Word puzzles –20Q game reversed –Concept – known –Keywords – the ones that would lead to the concept