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ℓ²-homology and planar graphs

Timothy A. Schroeder (2013)

Colloquium Mathematicae

In his 1930 paper, Kuratowski proves that a finite graph Γ is planar if and only if it does not contain a subgraph that is homeomorphic to K₅, the complete graph on five vertices, or K 3 , 3 , the complete bipartite graph on six vertices. This result is also attributed to Pontryagin. In this paper we present an ℓ²-homological method for detecting non-planar graphs. More specifically, we view a graph Γ as the nerve of a related Coxeter system and construct the associated Davis complex, Σ Γ . We then use a...

[unknown]

Nariya Kawazumi, Yusuke Kuno (0)

Annales de l’institut Fourier

[unknown]

Thomas Morzadec (0)

Annales de l’institut Fourier

[unknown]

Raimundo Araújo dos Santos, Maria A.B. Hohlenwerger, Osamu Saeki, Taciana O. Souza (0)

Annales de l’institut Fourier

[unknown]

Selim Ghazouani (0)

Annales de l’institut Fourier

θ -curves inducing two different knots with the same 2 -fold branched covering spaces

Soo Hwan Kim, Yangkok Kim (2003)

Bollettino dell'Unione Matematica Italiana

For a knot K with a strong inversion i induced by an unknotting tunnel, we have a double covering projection Π : S 3 S 3 / i branched over a trivial knot Π fix i , where fix i is the axis of i . Then a set Π fix i K is called a θ -curve. We construct θ -curves and the Z 2 Z 2 cyclic branched coverings over θ -curves, having two non-isotopic Heegaard decompositions which are one stable equivalent.

Λ -sphères

Jean Barge, Jean Lannes, François Latour, Pierre Vogel (1974)

Annales scientifiques de l'École Normale Supérieure

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