The model evaluates cars according to the following concept structure:
-> CAR : car acceptability
-> PRICE : overall price
-> buying : buying price
-> maint : price of the maintenance
-> TECH : technical characteristics
-> COMFORT : comfort
-> doors : number of doors
-> persons : capacity in terms of persons to carry
-> lug_boot : the size of luggage boot
-> safety : estimated safety of the car
buying : v-high, high, med, low
maint : v-high, high, med, low
doors : 2, 3, 4, 5-more
persons : 2, 4, more
lug_boot : small, med, big
safety : low, med, high