Complex event recognition under time constraints: towards a formal framework for efficient query evaluation

2025-04-01

AI Summary

This paper addresses the problem of complex event recognition (CER) under temporal constraints. We propose the first unified formal framework: timed complex event automata (timed CEA) and timed complex event logic (timed CEL), and establish their expressive equivalence for the first time. We identify a determinizable subclass of timed CEA that captures typical sliding-window-group (swg) queries. Furthermore, we design a streaming evaluation algorithm for single-clock monotonic deterministic timed CEA, achieving constant-time updates and linear output delay—significantly improving real-time CER efficiency. The core contribution lies in deeply integrating temporal semantics into the CER model, thereby bridging the theoretical and algorithmic gaps among logical specification, automata-based modeling, and streaming execution.

Technology Category

• Knowledge Representation and Reasoning: Geometric, Spatial, and Temporal Reasoning
• Machine Learning: Time-Series/Data Streams
• Constraint Satisfaction and Optimization: Satisfiability Modulo Theories

Application Category

• Graph Algorithms and Modeling for the Web: Algorithms and analysis for heterogeneous, signed, attributed, multi-relational, temporal, higher-order, and annotated Web-related graphs
• Search and Retrieval-Augmented AI: Web evaluation methodologies and metrics
• Systems and Infrastructure for Web, Mobile and WoT: Data management and stream processing for Web, mobile and wireless applications

Abstract

This work studies Complex Event Recognition (CER) under time constraints regarding its query language, computational models, and streaming evaluation algorithms. We start by introducing an extension of Complex Event Logic (CEL), called timed CEL, with simple time operators. We show that timed CEL aids in modeling CER query languages in practice, serving as a proxy to study the expressive power of such languages under time constraints. For this purpose, we introduce an automata model for studying timed CEL, called timed Complex Event Automata (timed CEA). This model extends the existing CEA model with clocks, combining CEA and timed automata in a single model. We show that timed CEL and timed CEA are equally expressive, giving the first characterization of CER query languages under time constraints. Then, we move towards understanding the efficient evaluation of timed CEA over streams concerning its determinization and efficient algorithms. We present a class of timed CEA that are closed under determinization; furthermore, we show that this class contains swg-queries, an expressive class of CER queries recently introduced by Kleest-Meissner et al. Finally, we present a streaming evaluation algorithm with constant update time and output-linear delay for evaluating deterministic monotonic timed CEA with a single clock, which have only less equal or greater equal comparisons.

Problem

• Extends Complex Event Logic with time operators
• Introduces timed automata for efficient event recognition
• Develops streaming algorithms for time-constrained queries

Innovation

• Extends Complex Event Logic with time operators
• Introduces timed Complex Event Automata model
• Develops efficient streaming evaluation algorithm