Abstract: The similarity problem of emergency events is a difficult problem to be solved when the occurred emergency events in case-based reasoning technology are used for the auxiliary decision making.Thus in the horizontal aspect, the scenario chain is constructed in the order of time sequence based on the key decision points scenario. And in the vertical aspect, the constitutive model of "event-scenario-emergency tasks-emergency action" is Put forward. Then based on the scenario chain similarity algorithm the problem of finding similar emergencies and coping strategies is solved. The similarity of the scenario chain includes the similarity of the whole scenario chain and scenario node. Considering that the emergency level effects the emergency response, the algorithm of the scenario chain similarity is designed, firstly from the similarity of the scenario chain structure in the two similar emergencies including the similarity of the emergency level and the number of nodes, then the similarity between semantic concepts including the scenario name set overall similarity and the attribute similarity of scenario node, and finally the two emergency scenario chains overall similarity with this formula:S_ij=[ω₁,ω₂,ω₃]·[S_ij^level,S_ij^Num,S_ij^Name]^T.When it comes to the similarity of disposal task and emergency action, the similarity of disposal tasks overall set under the specific situation is calculated, and then similarity of emergency actions which are selected from the highest similarity of the two disposal tasks is calculated, and finally set the union set of the highest similarity of emergency actions is set, and the whole through the formula:S_ab=[ω₁,ω₂,ω₃]·[S_ab^Task,S_ab^task,S_ab^Action]^T is gotten. This study enriches and develops the theory of "scenario-response", and provides technical inputs for the emergency decision making method.

Key words: decision, emergency, scenario chain, similarity