Chordal intersection representations
Lax560391.ChordalIntersectionRepresentation · concepts/Lax560391/ChordalIntersectionRepresentation.lean · lax-560391
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Definition
A chordal intersection representation is an indexed family of chordal graphs on the same vertex set whose edge intersection is the represented graph. Each factor is consequently a supergraph. Zero factors represent the complete simple graph.
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| 1 | import Lax560391.ChordalGraphs |
| 2 | |
| 3 | /-! |
| 4 | --- |
| 5 | title: Chordal intersection representations |
| 6 | type: definition |
| 7 | --- |
| 8 | A chordal intersection representation is an indexed family of chordal |
| 9 | graphs on the same vertex set whose edge intersection is the represented |
| 10 | graph. Each factor is consequently a supergraph. Zero factors represent |
| 11 | the complete simple graph. |
| 12 | -/ |
| 13 | |
| 14 | namespace Lax560391.ChordalIntersectionRepresentation |
| 15 | |
| 16 | structure ChordalIntersectionRepresentation {V : Type} |
| 17 | (G : SimpleGraph V) (k : ℕ) where |
| 18 | factors : Fin k → SimpleGraph V |
| 19 | chordal : ∀ i, Lax560391.ChordalGraphs.IsChordal (factors i) |
| 20 | represents : ∀ u v, u ≠ v → (G.Adj u v ↔ ∀ i, (factors i).Adj u v) |
| 21 | |
| 22 | end Lax560391.ChordalIntersectionRepresentation |
| 23 |
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