Integral start times suffice
Lax391470.IntegralStartTimes · concepts/Lax391470/IntegralStartTimes.lean · lax-391470
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Theorem
An instance has a feasible schedule with real start times if and only if it has one with integer start times. Rounding every start time up to the next integer preserves feasibility, because release times, deadlines and processing times are integers.
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| 1 | import Lax391470.Scheduling |
| 2 | |
| 3 | /-! |
| 4 | --- |
| 5 | title: Integral start times suffice |
| 6 | type: theorem |
| 7 | --- |
| 8 | An instance has a feasible schedule with real start times if and only if it has one with |
| 9 | integer start times. Rounding every start time up to the next integer preserves |
| 10 | feasibility, because release times, deadlines and processing times are integers. |
| 11 | |
| 12 | # Formalization notes |
| 13 | |
| 14 | The source defines a schedule as a real-valued assignment of start times and remarks |
| 15 | that, by discretization, start times can always be taken to be integers. This statement |
| 16 | is that remark. It is what licenses the rest of the submission to define feasibility over |
| 17 | the integers. |
| 18 | -/ |
| 19 | |
| 20 | namespace Lax391470.IntegralStartTimes |
| 21 | |
| 22 | open Lax391470.Scheduling |
| 23 | |
| 24 | /-- Real and integer start times decide the same instances. -/ |
| 25 | axiom realSchedulable_iff (I : Instance) : I.RealSchedulable ↔ I.Schedulable |
| 26 | |
| 27 | end Lax391470.IntegralStartTimes |
| 28 |
Formalization notes
The source defines a schedule as a real-valued assignment of start times and remarks that, by discretization, start times can always be taken to be integers. This statement is that remark. It is what licenses the rest of the submission to define feasibility over the integers.
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