S.Caschili and F.R.Medda goals. 54,41 model because they change routes according to demand for the goods they carry. Nested Each agent can be 55,5] Diversity Port alliances at national or systems considered as a and international level are nested system.Each internal clusters of ports.The same port system is part of model may belong to a cluster of ports something bigger, at national level and to a cluster thus each system of ports at inter-national level, can be a sub- but this category may not system of a bigger necessarily include all the ports to system. which it belongs within the national cluster. can apply such questions to the case of maritime shipping in order to forecast future configurations and prevent global breakdowns in national and international markets(Table 2 -Feature:Self-organization). The maritime shipping industry is comprised by several relevant sectors such as international maritime transport,maritime auxiliary services and port services;they have a fairly long history of co-operation since the 1990s with the formation of consortia and alliances.Each co-operation is regulated by a wide range of "national and international regulations responding to specific issues that have arisen as the international trading system has evolved'[33].The outcomes of these collaborations influence the setting of freight rates and shipping company tariffs.In light of the previous remarks,co-operation among agents (shipping companies,port authorities,and so on)should be included in the modelling(Table 2 -Features:Distributed control and Nested Systems). In particular,international economic alliances in trade agreements are influential in the definition of trade flows and development.For instance,China's admittance into the WTO has affected the bilateral negotiations between WTO countries and China itself as well as among former members (Table 2-Feature:Co-evolutionary and Self-organization),but other examples of international trade agreements show similar impacts on international trade processes (NAFTA among North American countries,MERCOSUR in South America, ASEAN-AFTA among five Asian countries,the Trans-Pacific Strategic Economic Partnership(TPP)in the Asian-Pacific region). On the basis of the observations discussed above,when we model shipping relationships trade agreement memberships should be included for two reasons:firstly,to understand the actual effects on agents involved in the agreements;and secondly,to understand the effects generated on agents who are not members of a specific trade bloc.In this regard,a CAS application on maritime international trade would help us to better assess the role of alliances in trade,the effects of the establishment of new alliances,and the admission of new members in existing agreements(Table 2-Feature:Emergence). The aforementioned are some of the questions a CAS application should potentially be able to answer when policy constraints are reckoned with the agents'behaviour modelling (Table 2 -Feature:Distributed control).Referring to Holland's classification,the modeller has to set up the internal model of each agent so that it takes into account the distinguishing factors an agent uses to direct its economic choices.For example,national and international port alliances are nested clusters of ports.A single port may belong to a cluster of ports at national level and also belong to a cluster of ports at international level.But not all ports in a national 10S. Caschili and F.R. Medda 10 goals. 54, 41 model because they change routes according to demand for the goods they carry. Nested systems Each agent can be considered as a system. Each system is part of something bigger, thus each system can be a sub￾system of a bigger system. 55, 5] Diversity and internal model Port alliances at national or international level are nested clusters of ports. The same port may belong to a cluster of ports at national level and to a cluster of ports at inter-national level, but this category may not necessarily include all the ports to which it belongs within the national cluster. can apply such questions to the case of maritime shipping in order to forecast future configurations and prevent global breakdowns in national and international markets (Table 2 – Feature: Self-organization). The maritime shipping industry is comprised by several relevant sectors such as international maritime transport, maritime auxiliary services and port services; they have a fairly long history of co-operation since the 1990s with the formation of consortia and alliances. Each co-operation is regulated by a wide range of “national and international regulations responding to specific issues that have arisen as the international trading system has evolved” [33]. The outcomes of these collaborations influence the setting of freight rates and shipping company tariffs. In light of the previous remarks, co-operation among agents (shipping companies, port authorities, and so on) should be included in the modelling (Table 2 – Features: Distributed control and Nested Systems). In particular, international economic alliances in trade agreements are influential in the definition of trade flows and development. For instance, China’s admittance into the WTO has affected the bilateral negotiations between WTO countries and China itself as well as among former members (Table 2 – Feature: Co-evolutionary and Self-organization), but other examples of international trade agreements show similar impacts on international trade processes (NAFTA among North American countries, MERCOSUR in South America, ASEAN-AFTA among five Asian countries, the Trans-Pacific Strategic Economic Partnership (TPP) in the Asian-Pacific region). On the basis of the observations discussed above, when we model shipping relationships trade agreement memberships should be included for two reasons: firstly, to understand the actual effects on agents involved in the agreements; and secondly, to understand the effects generated on agents who are not members of a specific trade bloc. In this regard, a CAS application on maritime international trade would help us to better assess the role of alliances in trade, the effects of the establishment of new alliances, and the admission of new members in existing agreements (Table 2 – Feature: Emergence). The aforementioned are some of the questions a CAS application should potentially be able to answer when policy constraints are reckoned with the agents’ behaviour modelling (Table 2 – Feature: Distributed control). Referring to Holland’s classification, the modeller has to set up the internal model of each agent so that it takes into account the distinguishing factors an agent uses to direct its economic choices. For example, national and international port alliances are nested clusters of ports. A single port may belong to a cluster of ports at national level and also belong to a cluster of ports at international level. But not all ports in a national