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A multisensor tactical threat assessment system is being developed by the US Army CECOM RDEC Intelligence and Electronic Warfare Directorate (lEWD). Roughly speaking, the current system consists of a tactical hypothesis generator and a hypothesis evaluation algorithm. The hypothesis generator is capable of developing complex multi-Actor tactical plans. Plans have a symbolic representation which is then instantiated with actual tactical data to produce an activity model. The hypothesis evaluation algorithm uses the activity model to synthesize possible Actor actions which may satisfy the plan goals. Multi-Actor plans are synthesized individually for each Actor. Thus, each Actor maintains his own peculiar "world-view' of the battlefield during the problem solving process. The resulting implementation is a highly distributed and parallel problem solver. This methodology assumes a deterministic relationship between Actor action execution and the Actor's digital feature space which is a raster picture element (pixel). Spatial changes caused by Actor action execution within a pixel are broadcast to other Actors within the domain using a standard AT BlackBoard (BB). Nondeterministic relationships between Actors are produced whenever the local spatial or temporal goals of two or more Actors conflict with one another. For example, inter-Actor conflict may be produced when two or more Actors attempt to move to the same pixel at the same instant of time. Actor movement can become deadlocked if both Actors cannot co-occupy the same pixel, i.e. ,the McNeil paradox. Recently, a realistic solution to the McNeil paradox was developed by the author. The solution algorithm uses Actor action execution information which has been posted on the BB to develop a global strategy which effectively mediates Actor conflicts. The approach is general enough to encourage the development of a general theory of Actor conflict, including both cooperative and adversarial Actor relationships. The author will show that for certain types of Actor conflicts the complexity of the BB inter-Actor conflict mediation algorithm is 0(n).
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