Disclosed is a method for determining tactical actions for protecting a reference entity with respect to a plurality of entities in a battlefield environment, the method including: segmenting the battlefield environment into a plurality of layers; associating actable deterrent systems with each layer; obtaining data representative of the probability, for each deterrent system, that the considered deterrent system deters an entity in the associated layer; providing, for each entity, the level of threat of the entity; and computing a cost function for determining the deterrent systems to be engaged by the reference entity for rendering extremal the cost function, the cost function being a function depending from the provided level of threat and the obtained data.
Please help me write a proper abstract based on the patent claims. CLAIM: 1-15. (canceled) 16. A method for determining tactical actions for protecting a reference entity with respect to a plurality of entities in a battlefield environment, the method comprising: segmenting the battlefield environment into a plurality of layers, associating actable deterrent systems with each layer, obtaining data representative of the probability, for each deterrent system, that the considered deterrent system deters an entity in the associated layer, providing, for each entity, the level of threat of said entity, and computing a cost function for determining the deterrent systems to be engaged by the reference entity for rendering extremal the cost function, the cost function being a function depending from the provided level of threat and the obtained data. 17. The method for determining according to claim 16, wherein, at the obtaining step, data representative of the nature of the entity are obtained. 18. The method for determining according to claim 16, wherein, at the computing step, the cost function depends at least from the product of the provided level of threat and the obtained data. 19. The method for determining according to claim 16, wherein at the obtaining step, data representative of the consumption of the considered deterrent system are obtained. 20. The method for determining according to claim 16, wherein at the computing step, the imposed engagement policies are taken into account. 21. The method for determining according to claim 16, wherein the method further comprises a step of associating with each layer a category of tactical actions that may be engaged by the reference entity. 22. The method for determining according to claim 16, wherein the method further comprises a step of associating at least one geographical parameter with each layer, said parameters comprising the distance range delimiting the layer, said distance range being associated with a begin range and an end range. 23. The method for determining according to claim 16, wherein the distance range associated with each layer is predefined and static. 24. The method for determining according to claim 16, wherein the distance range associated with each layer is dynamically defined depending on predefined criteria. 25. The method for determining according to claim 16, wherein the entities and the reference entity are ships. 26. A decision support method comprising the steps of: carrying out a method for determining tactical actions for protecting a reference entity with respect to a plurality of entities in a battlefield environment according to claim 16, generating tactical recommendations in association with the determined deterrent systems to be engaged. 27. A computer program comprising instructions for carrying out the steps of a method according to claim 16 when said computer program is executed on a suitable computer device. 28. A computer readable medium having encoded thereon a computer program according to claim 27. 29. A system for determining tactical actions for protecting a reference entity with respect to a plurality of entities in a battlefield environment, the system comprising: a calculator adapted to segment the battlefield environment into a plurality of layers, and an obtaining unit adapted to obtain data representative of the probability, for each deterrent system, that the considered deterrent system deters an entity in the associated layer, the calculator being further adapted to associate actable deterrent systems with each layer, to provide, for each entity, the level of threat of said entity and to compute a cost function for determining the deterrent systems to be engaged by the reference entity for rendering extremal the cost function, the cost function being a function depending from the provided level of threat and the obtained data. 30. A decision support system comprising a system for evaluating according to claim 29, the calculator being further adapted to generate tactical recommendations in association with the determined deterrent systems to be engaged.