1 A Semantic Metanetwork Vagan Terziyan University of Jyvaskyla, Finland

2 Creating and Managing Knowledge According to Different Levels of Possible Context - are among the basic abilities of an intelligent agent Data Knowledge Contexts Metacontexts Metaknowledge Meta-metaknowledge

3 Contents 4 Metasemantics 4 Metasemantic Network 4 Metasemantic Algebra of Contexts

4 Metasemantics

5 Semantic Predicate AiAi AjAj LkLk AiAi LkLk Relation (i  j) Property (i = j)

6 State of a Semantic Net

7 Structure of the Metasemantics Production Rules Temporal Rules Semantic Rules Semantic Network Metasemantics

8 Read more about Metasemantics in Terziyan V., Multilevel Models for Knowledge Bases Control and Their Applications to Automated Information Systems, Doctor of Technical Sciences Degree Thesis, Kharkov State Technical University of Radioelectronics, 1993.

9 Metasemantic Networks

10 Metasemantic Network (Semantic Metanetwork) is considered formally as the set of semantic networks, which are put on each other in such a way that links of every previous semantic network are in the same time nodes of the next network A Metasemantic Network

11 An Example of a Semantic Metanetwork

12 How it Works In a Semantic Metanetwork every higher level controls semantic structure of the lower level. Simple controlling rules might be, for example, in what contexts certain link of a semantic structure can exist and in what context it should be deleted from the semantic structure. Such multilevel network can be used in an adaptive control system which structure is automatically changed following changes in a context of the environment. The algebra for reasoning with a semantic metanetwork is also developed.

13 Published and Further Developed in Terziyan V., Multilevel Models for Knowledge Bases Control and Their Applications to Automated Information Systems, Doctor of Technical Sciences Degree Thesis, Kharkov State Technical University of Radioelectronics, Terziyan V., Puuronen S., Reasoning with Multilevel Contexts in Semantic Metanetworks, In: P. Bonzon, M. Cavalcanti, R. Nossun (Eds.), Formal Aspects in Context, Kluwer Academic Publishers, 2000, pp

14 Metasemantic Algebra of Contexts

15 Semantic predicate describes a piece of knowledge (relation or property) by the expression: if there is knowledge that a relation with name L k holds between objects A i and A j Metasemantic Algebra: A Semantic Predicate

16 Example of Knowledge

17 Semantic Operations: Inversion

18 Semantic Operations: Negation P(,, ) = false, it is the same as: P(,, ) = true.

19 Semantic Operations: Composition If it is true: P(,, ) and P(,, ), then it is also true that: P(,, ).

20 Semantic Operations: Intersection + =.

21 Semantic Operations: Interpretation

22 Interpreting Knowledge in a Context

23 Example of Interpretation The interpreted knowledge about the relation between A 1 and A 3 taking all contexts and metacontexts into account is as follows:

24 Decontextualization Suppose that your colleague, whose context you know well, has described you a situation. You use knowledge about context of this person to interpret the “real” situation. Example is more complicated if several persons describe you the same situation. In this case, the context of the situation is the semantic sum over all personal contexts.

25 Context Recognition Suppose that someone sends you a message describing the situation that you know well. You compare your own knowledge with the knowledge you received. Usually you can derive your opinion about the sender of this letter. Knowledge about the source of the message, you derived, can be considered as certain context in which real situation has been interpreted and this can help you to recognize a source or at least his motivation to change the reality.

26 Lifting (Relative Decontextualization) This means deriving knowledge interpreted in some context if it is known how this knowledge was interpreted in another context.

27 Published and Further Developed in Terziyan V., Multilevel Models for Knowledge Bases Control and Their Applications to Automated Information Systems, Doctor of Technical Sciences Degree Thesis, Kharkov State Technical University of Radioelectronics, Terziyan V., Puuronen S., Reasoning with Multilevel Contexts in Semantic Metanetworks, In: P. Bonzon, M. Cavalcanti, R. Nossun (Eds.), Formal Aspects in Context, Kluwer Academic Publishers, 2000, pp