AIAA 2010-3503
AIAA Infotech@Aerospace 2010
20 - 22 April 2010, Atlanta, Georgia
Detecting Emergent Behaviors with Semi-Boolean Algebra
Peter Haglich1 and Christopher Rouff 2
Lockheed Martin Advanced Technology Laboratories, Arlington, VA, 22203, USA
and
Laura Pullum3
Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
Aerospace and military systems are becoming increasingly interconnected. In turn, their
collective behavior is more difficult to predict. The emergent properties of systems of
systems make them powerful, but also more difficult to design, assure proper behavior,
operate correctly, and ensure they have no new security holes. Learning and adaptation
causes additional concerns. Emergent behavior patterns cannot be fully predicted through
the use of traditional system development methods, including testing and model checking. In
addition, self-organization can occur as individual systems optimize to address inefficiencies
in the larger system. Designing for and detecting emergent behavior has not been addressed
in current systems development methodologies. This paper gives background on approaches
for modeling and verifying emergent behavior and discusses the use of semi-Boolean algebra
as a means for detecting emergence in combined behaviors. Semi-Boolean algebra is a
generalization of the Boolean algebra by weakening the requirement that any two elements
have a common upper bound. The paper also shares an example approach for modeling and
verifying emergent behavior and describes several ways to detect emergent behavior with
this technique.
I
I. Introduction
NTERCONNECTED systems are becoming standard in aerospace, military, and commercial applications. As
systems are interconnected, their combined behavior is far more complex than each individual system in isolation.
Unexpected self-organizing or emergent behaviors can result from the combination of state spaces of the systems1,2.
Bonabeau and others who studied self-organization in social insects, stated, ―complex collective behaviors may
emerge from interactions among individuals that exhibit simple behaviors.‖ He described emergent behavior as, ―a
set of dynamical mechanisms whereby structures appear at the global level of a system from interactions among its
lower-level components3,4,5.‖ Heylighen stated that, ―complex systems consist of many parts that are connected
through their interaction.‖ Heylighen goes on to say that, ―their components are both distinct and connected, both
autonomous and to some degree mutually dependent6.‖
The idea of emergence is well known from biology, economics, and other scientific areas. Although they
encounter it regularly, the concept is not as well understood by computer scientists and engineers. Parunak and
Vanderbok describe emergent behavior in systems as, ―system behavior that is more complex than the behavior of
the individual components … often in ways not intended by the original designers.7‖ This means when interacting
components of a system, whose individual behavior is well understood, are combined within a single environment,
they can demonstrate unforeseen or inexplicable behavior. Consequently, making changes to components of a
system of systems, or replacing a sub-system within a system of systems, may often have unforeseen, unexpected,
and completely unexplained ramifications for overall system behavior and the behavior of other subsystems.
The emergent properties of systems of systems make them powerful, but at the same time make them more
difficult to design, assure proper behaviors emerge, operate correctly, and ensure they have no new security holes.
Learning and adaptation cause additional concerns because emergent behavior patterns simply cannot be fully
1
Senior Engineer, Informatics Laboratory, 4301 N. Fairfax Drive, Suite 500
Engineering Management, Informatics Laboratory, 4301 N. Fairfax Drive, Suite 500, AIAA Member
3
Sr. Comp. Sci. Researcher, Computational Sciences and Eng. Division, 1 Bethel Valley Road, AIAA Member
2
1
American Institute of Aeronautics and Astronautics
Copyright © 2010 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.