The Dynamic Controllability of Conditional STNs with Uncertainty

TL;DR

This paper introduces a new formal framework called CSTNU that integrates temporal constraints, observations, actions, and uncertainty, enabling automated reasoning in complex, uncertain processes like business and medical workflows.

Contribution

It defines the CSTNU model, generalizes existing concepts of dynamic controllability, and proposes sound constraint-propagation rules for checking controllability in this new framework.

Findings

CSTNU combines features of STN, CSTP, and STNU.

A generalized notion of dynamic controllability is introduced.

Sound rules for controllability checking are proposed.

Abstract

Recent attempts to automate business processes and medical-treatment processes have uncovered the need for a formal framework that can accommodate not only temporal constraints, but also observations and actions with uncontrollable durations. To meet this need, this paper defines a Conditional Simple Temporal Network with Uncertainty (CSTNU) that combines the simple temporal constraints from a Simple Temporal Network (STN) with the conditional nodes from a Conditional Simple Temporal Problem (CSTP) and the contingent links from a Simple Temporal Network with Uncertainty (STNU). A notion of dynamic controllability for a CSTNU is defined that generalizes the dynamic consistency of a CTP and the dynamic controllability of an STNU. The paper also presents some sound constraint-propagation rules for dynamic controllability that are expected to form the backbone of a dynamic-controllability-checking algorithm for CSTNUs.