Extending the Range of Temporal Specifications of the Run-Time Event Calculus

Periklis Mantenoglou, Alexander Artikis

Abstract: Composite event recognition (CER) frameworks reason over streams of low-level, symbolic events in order to detect instances of spatio-temporal patterns defining high-level, composite activities. The Event Calculus is a temporal, logical formalism that has been used to define composite activities in CER, while RTEC_{∘} is a formal CER framework that detects composite activities based on their Event Calculus definitions. RTEC_{∘}, however, cannot handle every possible set of Event Calculus definitions for composite activities, limiting the range of CER applications supported by RTEC_{∘}. We propose RTEC_{fl}, an extension of RTEC_{∘} that supports arbitrary composite activity specifications in the Event Calculus. We present the syntax, semantics, reasoning algorithms and time complexity of RTEC_{fl}. Our analysis demonstrates that RTEC_{fl} extends the scope of RTEC_{∘}, supporting every possible set of Event Calculus definitions for composite activities, while maintaining the high reasoning efficiency of RTEC_{∘}.