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Dipartimento di Elettronica e Informazione Politecnico di Milano prof. Elisabetta Di Nitto 20133 Milano (Italia) Piazza Leonardo da Vinci, 32 Tel. (39) 02-2399.3400 Fax (39) 02-2399.3411 Software Engineering II 18 January 2013 Last Name First Name Id number (Matricola) Note 1. The exam is not valid if you don’t fill in the above data. 2. Write your answers on these pages. Extra sheets will be ignored. You may use a pencil. 3. The use of any electronic apparatus (computer, cell phone, camera, etc.) is strictly forbidden. 4. You cannot keep a copy of the exam when you leave the room. 2 Question 1 Alloy (7 points) The civil protection department wants to build a system to support management of crises due to natural events such as earthquakes, inundations and the like. During a crisis first aid units have to be distributed in the affected territory in such a way that each area in the territory is controlled by at least one unit. After the crisis the refunding requests by citizens need to be evaluated and fulfilled or discharged, depending on the outcome of the analysis. We aim at writing an Alloy specification for this system. Answer to all points below: 1. What are the concepts that we should represent as signatures? Please provide a motivation for your answer. 2. Define the signature you have identified by providing an explanation for all attributes that you introduce. 3. Define all facts that are needed to maintain the consistency and the integrity of your model (if any) and explain in words what you mean by each of them. 4. Define two facts that describe the situations occurring during crisis and after crisis. In particular, the during crisis fact should ensure that each area in the territory is supported by a first aid unit. The after crisis fact should ensure that…