Optimal Allocation Of Anti-terrorism Defensive Resource Based On Game Theory

Judging from the current terrorism situation,attack targets gradually turn to soft targets,such as civilian,commercial facilities and so on.Terrorist activities tend to be“globalization” and “decentralization”.“Lone Wolf” attacks and “Suicide”attacks have increasingly become the important means of terrorist activities.Due to the transformation of targets and attack modes,it is very difficult for the government to crack down on terrorist groups actively,comprehensively and targeted.As a result,the defense against terrorism will become more important.It is a significant tool for optimal defensive resource allocation to use risk-based method,because we cannot adequately protect all targets within limited resource.Different from natural disasters,terrorist activities belong to a kind of subjective,intentional behavior.Thus,terrorism risk need to consider the “smart” and“adaptive” characteristic of terrorists.This thesis aims to design a reasonable terrorism risk assessment framework and examine the optimal defensive strategy based on game theory,in order to provide theoretical support for the decision-making of the government’s anti-terrorism defense.The main research contents are summarized as below:(1)After analysising and summarizing the research progress and trend of terrorism risk assessment method,this thesis presents a semi-quantitative terrorism risk assessment framework,including the description about target characteristics,scenario identification,consequence assessment,vulnerability assessment,threat assessment,risk assessment and risk management.Defender’s capabilities are quantified from two dimensions of investments and defensive efficiency,and are considered in the detection probability model based on search theory and the success probability model of disposal based on contest success function,in order to evaluate terrorism risk.(2)The construction of terrorism risk models and the analysis of anti-terrorism game.First,terrorism risk model considering defensive type is established.Under the hypothesis of single target attack,complete information game and incomplete information game are explored.Second,terrorism risk model considering the type of defense resources is established.Under the hypothesis of multi-target target attack,Games with the same target valuations and games with different target valuations are examined.Finally,space relationship is considered into the terrorism risk model.Under the hypothesis of single target attack and multi-target target attack,the anti-terrorism games of series system and series-parallel system are analyzed.(3)Validity verification of terrorism risk models and anti-terrorism games.First,the simulation results of equilibrium strategies are analyzed under twelve specific scenarios,including the comparative analysis between different attack modes,the comparative analysis between “soft targets” and “hard targets”,the comparative analysis between “adequately resourced” terrorist groups and “poorly resourced” terrorist groups,the comparative analysis between single target attack and multi-target attack,the comparative analysis between series system,parallel system and series-parallel system,and so on.Second,the rationalities of simulation results are interpreted though the terrorism data,cases of terrorist attack,observed defensive phenomena,in order to verify the validity of these models.Finally,behavioral characteristics between defenders and terrorists are summarized,to support defensive resource allocation.(4)A specific railway station system is simulated analyzed to make terrorism risk assessment framework more operable,hoping to have a better insight to the railway station anti-terrorism defense.First,threat scenarios and uncertainties of terrorist attacks at the railway station are identified based on historical data and expert knowledge.Basic information about the railway station are collected with the aid of field study,such as defensive resource,the stream of people,the railway station plan and facility layout,etc.The quantitative methods or models are designed to mensure each indicator.Second,under a specific attack mode,the terrorism risk of each area of the system is evaluated,and critical paths and critical areas are identified.Finally,the current defensive resource allocation is optimized through game theory,and the anti-terrorism defensive optimization strategy of railway station are concluded.The main research conclusions and findings are summarized as below:(1)There is a critical value for the optimal amount of attack resources.If resources of terrorist are more than the critical value,the optimal strategy of both sides will reach steady state.(2)Under the condition that the resources of terrorists are little or most likely little in a single target attack scenario: If the disposal efficiencies between two targets are close and the detection efficiencies between two targets are great difference,the optimal defensive strategy need to allocate more resources to the target within lower disposal efficiency,even if that target’s value is small;If the disposal efficiencies between two targets are great difference and the detection efficiencies between two targets are close,the optimal defense strategy need to allocate more resources to the target within lower high value.(3)Under the condition of a multi-target attack scenario: if the resources of terrorists are abundant,the strategy of multi-target attack will be selected by terrorists and the equilibrium strategies depend on the defender’s value estimation and defense efficiencies;Only when the resources of terrorists are little,the strategy of a single target attack can be selected by terrorists.(4)Considing the space relationship between targets: The phenomenons of prepositive detection and postpositive detection may possibly appear in series system and parallel system,which makes all detection resources to converge on key targets.The series relationship between targets provides opportunities for targets’ defense cooperation,which makes the defense effect of series system and parallel system are better than that of series-parallel system.It can also enhance the defense effect of a system if the parallel relationship is converted to series relationship.