Work Plan

1. Event Stream Constraint Language (ESCL)
2. Instantiating Hierarchical Timed Automata (IHTA)
3. Derivation of ESCL constraints from IHTA
4. Propagation of ESCL constraints with respect to CEP queries
5. Derivation of ESCL constraints from CEP queries independently from other constraints
6. Subsumption of CEP conjunctive queries
7. Semantic rewriting of CEP queries with respect to ESCL constraints
8. Choice of one of the alternatively semantically optimized queries to evaluate instread of each initial query using cost models
9. Implementation, experimental evaluation, visual editor