1. partners CTXML - Context Markup Language - Luciano Serafini 1 Antonia Dona’ 2 Paolo Bouquet 3 1 ITC-irst, via Sommarive 18, I-38050 Trento-Povo, Italy 2 ITC-irst, via Sommarive 18, I-38050 Trento-Povo, Italy 3 University of Trento, via Sommarive 14, I-38050 Trento-Povo, Italy

2. 2 Overview  Context Space (Natural Environment for contexts)  Structure of a Context  Structure of a mapping  Building and modifyng contexts and mappings in a context space

3. 3 Trains Quantum Computinjg Transport Logis- tics Maps Train to Transp Maps 2 Log. Log 2 maps Transp. to logist. UPS logistics Log 2 ups 2 Log. To UPS 1 Context space

4. 4  A context space is composed of –a set of context C; –a set of mappings M between contexts.  For each mapping m in M, there are two context c 1 and c 2 such that: –c 1 is the source context of m; –c 2 is the target context of m.

5. 5 Context Space: contexts  A context has an owner (agent) who belongs to a group;  A context has a position in a context space (address);  A context can move (i.e., it changes its address);  Contexts can appear in, or disappear from a contexts space

6. 6 Context Space: mappings  A mapping has an owner (agent) who belongs to a group;  A mapping has a position in a context space (address);  A mapping can move (i.e., it changes its address);  Mappings can appear in, or disappear from a contexts space.

7. 7 Mappings between contexts  Mapping are directional. The mapping from c 1 to c 2 can be different from the inverse of the mapping from c 2 to c 1. –c 1 :cars is mapped in c 2 mezzo di trasporto –But not vice versa  Mappings are not transitive. I.e., the mapping from c 1 to c 3 is not the composition of the mapping from c 1 to c 2, with the mapping from c 2 to c 3.  There can be more (different) mappings from a context c 1 to a context c 2. –each of which corresponds to a different way to map c 1 in c 2.

8. 8 Context and Mappings main Structure  A context is composed of: –Header –Content –Reference to the mappings entering in or exiting from the context  A mapping is composed of: –Header –Content –Reference to the context between which the mapping is defined  Attributes for both contexts and mappings are: –Unique identifier –Reference to the address manager –Status (draft, approved, obsolete, freezed …)

9. 9 Context and Mapping Header  The header of a context/mapping contains –List of owners –List of groups –Information about security –The history

10. 10 Context context  Two level of description –Abstract description: It is the abstract description of the mathematical (logical) structure. Clean model of what is the content of a context. (e.g., FOL, DL, concept hierarchies, ontologies, etc.). –Concrete description: it is a specific syntax (XML, XML-schema, DTD, prolog …) that allows one to describe the abstract structure in a text file. (The same abstract description can be concretized in different ways by different (or the same) syntax)  Different context can have different abstract and concrete description of their content.

11. 11 Context context: a first proposal  Abstract description = Concept hierarchies  Concrete description = XML-schema

12. 12 Concept hierarchies  A concept hierarchy is a graph where –C is a set of concepts –E is a set of edge between concepts –Each element of C and E is labeled with a label (the same label can be associated to different concepts and edges) –The set of labels L are partitioned in wo subsets L H = Hierarchical labels, and L G = General (non hierarchical labels) –The sub-graph of H restricted to the arcs with hierarchical labels, must be an acyclic graph.

13. 13 Concept Hierarchies: labels  The set L H of hierarchical labels contains the labels: –Is-a –Part-of –Undef (representing either is-a or part-of)  The set of labels L G can contain any label different from Is-a Part-of, and Undef.

14. 14 Context Hierarchy: Example

15. 15 Concrete description of CH  The content of a context is represented via XML shema: –Concepts = complextype –Is-a = extension –Part-of = element –General relations are reified

16. 16 Concrete description of CH: Example...

17. 17 XML schema for Context  It is composed of two parts:  XML schema for the header  XML schema for the content –Notice that this is an XML-schema that describes another XML- schema

18. 18 Why we propose XML -schema?

19. 19 Why we propose XML schema for Content Description  Is-a relation is built in (by the tag extension)  Part-of relation is built in (by the tag element)  Concepts in KR usually refers to sets of element. This is analogous with the fact that complextyper define a type of elements (a set of elements matching this type)  Document can be associated to a concept, by writing an element of the type of the concept that summarizes (refers to) the document  XML schema is itself XML and can be described by XML schema.(context about context…but this might not be immediately useful)  Software for XML schema can be refused

20. 20 Next steps  Context Space  Structure of a context  Structure of a mapping  Building and modifying contexts and mappings in a context space