Lax18.PartitionEnergyMonotonicity
Monotonicity of partition energy under refinement
concepts/Lax18/PartitionEnergyMonotonicity.lean · lax-18
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Theorem
If one graph partition refines another, then its weighted mean-square density is at least that of the coarser partition. This is the finite conditional variance inequality underlying the energy-increment proof.
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| 1 | import Lax18.PartitionEnergy |
| 2 | |
| 3 | /-! |
| 4 | --- |
| 5 | title: Monotonicity of partition energy under refinement |
| 6 | type: theorem |
| 7 | --- |
| 8 | If one graph partition refines another, then its weighted mean-square density |
| 9 | is at least that of the coarser partition. This is the finite conditional |
| 10 | variance inequality underlying the energy-increment proof. |
| 11 | -/ |
| 12 | |
| 13 | namespace Lax18.PartitionEnergyMonotonicity |
| 14 | |
| 15 | open Lax18.FiniteGraphPartitions |
| 16 | open Lax18.PartitionEnergy |
| 17 | |
| 18 | universe u |
| 19 | |
| 20 | /-- Refining a partition cannot decrease its energy. -/ |
| 21 | axiom partitionEnergy_mono_of_refines : |
| 22 | ∀ {V : Type u} [Fintype V] [DecidableEq V] |
| 23 | (G : SimpleGraph V) (P Q : VertexPartition V), |
| 24 | Refines Q P → partitionEnergy G P ≤ partitionEnergy G Q |
| 25 | |
| 26 | end Lax18.PartitionEnergyMonotonicity |
| 27 |
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