## 2 Background  
Because it is not feasible to undertake a real simulation under a series of foreseen and unforeseen circumstances, the only plausible way to address the validation of a navy ship evacuation plan or protocol is to use a nondeterministic simulator. To quantify and validate the characteristics of the scenario we configured, the IMO has progressively adopted microscopic models in its standard to emulate the evacuation process on board a ship. In fact, the MaritimeEXODUS application [17] version 4.0 (manufactured by the University of Greenwich, London, UK) is referenced by the IMO as a validation tool in its MSC/Circ.1238 [18] and, therefore, in the NSC [13]. The MaritimeEXODUS application has great capacity for configuring the general layout of a naval platform in real situations (breakdowns, heel, disabled spaces, etc.) as simulation scenarios, in addition to the intervening agents that emulate the embarked population. This simulator employs a network of nodes that like tiles, determine the transit or occupation options of a single agent at a specific time. Each agent then goes to a specific sink node that, in turn, emulates a lifeboat. The agents, characterized as instantiated objects and configured with attributes provided by the population distribution of a military ship, allow us to simulate the evacuation process of the population on board the ship. The MaritimeEXODUS simulator implements an internal clock, which reevaluates and relocates the intervening agents in the corresponding adjacent tiles throughout the scenario every twelfth of a second until they finally reach the designated sink node (lifeboat). MaritimeEXODUS also defines the movement of an agent through routes previously established by the operator or by setting the criterion of the shortest path (distance) as a reference. After running a sufficient number of simulations of the evacuation process and analyzing the results, we can confirm that the dimensions of the ship and the population on board do not influence the configuration capacity or power of the simulator, provided that the integrity of the network of predefined evacuation routes is not affected by unexpected failures. This approach, however, is not realistic, because it does not consider the characteristics of an emergency event. The order to abandon ship will be given by the command as a result of an emergency or breakdown, meaning that the physical integrity of the ship and the embarked population are at risk. Therefore, the network of escape routes will inevitably be affected. Figure 1: Spanish navy staff age by category and gender in 2007 [14]. The MaritimeEXODUS simulator is a powerful and versatile simulation tool that facilitates the configuration of a scenario and simulation of a process. The results can validate compliance with the precepts, provisions, and current regulations of a naval ship evacuation plan. However, this tool is not adequate to carry out the simulation of an unforeseen situation due to the excessive time needed to configure such a specific scenario. As an alternative approach, the concept of dynamic evacuation, published in [19], is applied to model a dynamic scenario, emulating the general layout of a naval platform. This dynamic model admits partial restrictions on its structure to include those resulting from an unexpected breakdown or emergency. To address the optimization problem, a succession of methods is implemented to emulate an optimal evacuation process on board a worship. This is accomplished through the interaction of a dynamic structure (dynamic graph) modeling the reference platform and several agents representing the embarked contingent. Once the environment has been configured and the intervening agents have been monitored, a method supported by a graph vertex covering algorithm is implemented [20]. This method computes the minimum evacuation cost (time) estimated at each vertex--that is, the minimum cost attributed to an agent located at that vertex to reach its specific sink vertex on the graph.