---
title: "Managing Temporal Uncertainty Through Waypoint Controllability"
authors:
  - "Paul H. Morris"
  - "Nicola Muscettola"
doi: ""
url: "https://ijcai.org/proceedings/1999/178"
pdf: "https://ijcai.org/proceedings/1999/0178.pdf"
venue: "Proceedings of the Sixteenth International Joint Conference on Artificial Intelligence"
year: 1999
pages: "1253-1257"
track: "Temporal Reasoning"
keywords:
---

# Managing Temporal Uncertainty Through Waypoint Controllability

Paul H. Morris, Nicola Muscettola

*Proceedings of the Sixteenth International Joint Conference on Artificial Intelligence*, pages 1253-1257.

## Abstract

Simple Temporal Networks have proved useful in applications that involve metric time. However, many applications involve events whose timing is not controlled by the execution agent. A number of properties relating to overall controllability in such cases have been introduced in [Vidal and Ghallab , 1996] and [Vidal and Fargier, 1997], including Weak and Strong Controllability. We derive some new results concerning these properti es. In particular, we prove the negation of Weak Controllability is NP-hard, confirming a conjecture in [Vidal and Fargier, 1997]. We also introduce a more general controllability property of which Weak and Strong Controllability are special cases. A propagation algorithm is provided for determining whether the property holds, and we identify tractable cases where the algorithm runs in polynomial time.