Keyhole Adversarial Plan Recognition for Recognition of Suspicious and Anomalous Behavior

Dorit Avrahami-Zilberbrand, Gal A. Kaminka

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

9 Scopus citations


Adversarial plan recognition is the use of plan recognition in settings where the observed agent is an adversary, having plans or goals that oppose those of the observer. It is one of the key application areas of plan-recognition techniques. There are two approaches to adversarial plan recognition. The first is suspicious activity recognition; that is, directly recognizing plans, activities, and behaviors that are known to be suspect (e.g., carrying a suitcase, then leaving it behind in a crowded area). The second is anomalous activity recognition in which we indirectly recognize suspect behavior by first ruling out normal, nonsuspect behaviors as explanations for the observations. Different challenges are raised in pursuing these two approaches.In this chapter, we discuss a set of efficient plan-recognition algorithms that are capable of handling the variety of challenges required of realistic adversarial plan-recognition tasks. We describe an efficient hybrid adversarial plan-recognition system composed of two processes: a plan recognizer capable of efficiently detecting anomalous behavior, and a utility-based plan recognizer incorporating the observer's own biases-in the form of a utility function-into the recognition process. This allows choosing recognition hypotheses based on their expected cost to the observer. These two components form a highly efficient adversarial plan recognizer capable of recognizing abnormal and potentially dangerous activities. We evaluate the system with extensive experiments using real-world and simulated activity data from a variety of sources.

Original languageEnglish
Title of host publicationPlan, Activity, and Intent Recognition
Subtitle of host publicationTheory and Practice
PublisherElsevier Inc.
Number of pages33
ISBN (Print)9780123985323
StatePublished - Mar 2014

Bibliographical note

Funding Information:
We thank the anonymous reviewers and this book’s editors for their very valuable and detailed comments on early drafts of this chapter. This research was carried out with partial support from the Israeli Ministry of Commerce’s AVNET Consortium and the Israel Science Foundation , Grant #1511/12 . As always, thanks to K. Ushi.


  • Adversarial plan recognition
  • Anomalous plan recognition
  • Suspicious plan recognition
  • Utility-based plan recognition


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