; Checks whether at least one pitstop will be done and the car
; gets new tyres at least once.
;
; 1. Get the list of tyre compounds used at the different pitstops
;    with "pitstopTyreCompounds".
; 2. Compute the "length" of this list.
; 3. The scenario is valid, if the length of this list is larger than
;    zero, actually meaning that tyres have been changed at least once.

validScenario() <= pitstopTyreCompounds(?tyreCompounds), length(?tyreCompounds, ?length), ?length > 0