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Require a positive floor count - #245
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| Elevator, \* The set of all elevators | ||
| FloorCount \* The number of floors serviced by the elevator system | ||
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| ASSUME FloorCountIsInteger == FloorCount \in Int |
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@Qian-Cheng-nju Shouldn't Int be replaced with Nat \ {0}, given that the set of valid floors is defined as Floor == 1 .. FloorCount?
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Yes, that makes sense. I'll change it to Nat \ {0} and update the assumption name.
Signed-off-by: Qian-Cheng-nju <Qian-Cheng-nju@users.noreply.github.com>
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FloorCountis used inFloor == 1..FloorCount, but its domain is not stated. A Boolean value fails during interval evaluation; zero or negative values leaveFloorempty, soInithas no states when there are people or elevators.Add
ASSUME FloorCountIsPositive == FloorCount \in (Nat \ {0})to require at least one floor. This adds no upper bound and leaves the actions and invariants unchanged.The shipped
ElevatorSafetySmallandElevatorLivenessMediummodels pass with the same 4,122 distinct states. Parameter checks reject zero, negative and Boolean values before initialization, and accept 1, 2 and 1,000,000. Two focused TLAPS lemmas check that moving one floor toward a destination stays inFloor(six obligations,--strict --nofp). SANY passes for both modules.