- Extends Definition 1.5 (tire graph) to allow either B_out or B_in to
be a single vertex (a "degenerate" boundary); the tire is then a
triangulated disk with that vertex as apex.
- Adds Remark 1.6 with vertex/edge/triangle counts for both the
non-degenerate (annulus) and degenerate (disk) cases.
- Adds Lemma 1.7 (tire-component lemma): for a maximal planar graph G
with level source S and depth d ≥ 0, every connected component C' of
the dual subgraph on dual vertices of depth d induces a subgraph C
on G that is a tire graph; its two boundary parts are the level-d
and level-(d+1) induced subgraphs (in either order), and its
triangular faces are exactly the faces of G in F_{C'}.
- Adds Remark 1.8 noting the d=0 degenerate-source case as an example.
- Adds a figure (fig_tire_example.png) illustrating the definition with
m=6 outer cycle, k=4 inner cycle, one chord in O, plus a legend
identifying B_out, B_in, O's chord, and E_ann.
- Adds experiments/tire_def_figure.py to regenerate the figure.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
didericis
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