Distance to interval graphs
Lax560391.DistanceToInterval · concepts/Lax560391/DistanceToInterval.lean · lax-560391
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Definition
The minimum number of vertices whose deletion leaves an intersection graph of nonempty closed intervals on the real line.
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| 1 | import Lax560391.IntervalGraphs |
| 2 | import Mathlib.Combinatorics.SimpleGraph.Finite |
| 3 | import Mathlib.Order.Lattice.Nat |
| 4 | |
| 5 | /-! |
| 6 | --- |
| 7 | title: Distance to interval graphs |
| 8 | type: definition |
| 9 | --- |
| 10 | The minimum number of vertices whose deletion leaves an intersection graph of |
| 11 | nonempty closed intervals on the real line. |
| 12 | -/ |
| 13 | |
| 14 | namespace Lax560391.DistanceToInterval |
| 15 | |
| 16 | open Lax560391.IntervalGraphs |
| 17 | |
| 18 | noncomputable def distanceToInterval {V : Type} [Fintype V] [DecidableEq V] |
| 19 | (G : SimpleGraph V) : ℕ := |
| 20 | sInf {k : ℕ | ∃ S : Finset V, (S.card = k) ∧ |
| 21 | (IsInterval (G.induce {v | v ∉ S}))} |
| 22 | |
| 23 | end Lax560391.DistanceToInterval |
| 24 |
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