Conjecture on nonseparating cycle types in nonorientable triangulations

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Let NgN_g denote the nonorientable surface of Euler genus gg. A nonseparating cycle is one-sided when its neighborhood is a Möbius band, two-sided otherwise; it is orientable-leaving when deleting it leaves an orientable surface, and nonorientable-leaving otherwise.

Conjecture on nonseparating cycle types. If g≥3g \geq 3 is odd, every triangulation of NgN_g has a nonseparating cycle that is one-sided and orientable-leaving, one that is one-sided and nonorientable-leaving, and one that is two-sided and nonorientable-leaving. If g≥4g \geq 4 is even, every triangulation of NgN_g has a nonseparating cycle that is one-sided and nonorientable-leaving, one that is two-sided and orientable-leaving, and one that is two-sided and nonorientable-leaving.

The assertion extends the verified low-genus pattern for N1N_1, N2N_2, N3N_3, and N4N_4. No proof or counterexample is supplied for the stated general ranges.

References

Primary source

Thom Sulanke, “Irreducible triangulations of low genus surfaces”, arXiv:math/0606690 (2006).

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