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Research notes on every problem, and a library of the papers behind them. Built from the open erdos repository.

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Statement

Here m(n)m(n) is the minimum number of edges of a pancyclic graph on nn vertices, one with a cycle of every length from 33 to nn (p. 1).

Proposition 2 (p. 3). "m(n+1)≤m(n)+2m(n+1)\le m(n)+2 for all n≥3n\ge3"

Source. S. Griffin, Minimal pancyclicity, arXiv:1312.0274v1 (1 December 2013; 6 pages), the only arXiv version; Proposition 2 and its proof on p. 3. A preprint. The edition read is identified in the source digest.

Read depth. Claims checked: the statement and its proof were read on the page image of p. 3, and the proof's single step was followed.

Proof pointer

In this page's words: take a minimal pancyclic graph on nn vertices with Hamiltonian cycle v1v2⋯vnv_1v_2\cdots v_n and add a vertex vn+1v_{n+1} joined to vnv_n and v1v_1. The old cycles survive, giving every length from 33 to nn, and v1⋯vnvn+1v1v_1\cdots v_nv_{n+1}v_1 has length n+1n+1, so the new graph is pancyclic with m(n)+2m(n)+2 edges (p. 3).

Dependencies

None beyond the definitions.

Bears on

  • Problem 1016: in the problem's notation h(n+1)≤h(n)+1h(n+1)\le h(n)+1 for all n≥3n\ge3, a step-by-step bound on the growth of h(n)h(n); it does not bear on the asymptotic question.