Adds fig_partial_tire_dual_bridge.png beneath the existing partial-
tire-dual figure (Figure 3). The new figure shows a tire graph
whose inner outerplanar O has a bridge:
B_out = triangle on {0, 1, 2};
O = triangle {3, 4, 5} plus pendant edge 5-6 (the bridge);
annular triangulation with 8 triangles (constructed by hand).
Key contrast with the previous figure: because both faces incident
to the bridge are annular triangles, the bridge contributes an
INTERIOR DUAL EDGE rather than two leaves. Consequently the
interior dual subgraph is no longer a single (n+m)-cycle (as in
Prop 1.8 for spoke-only tires) but a theta graph: two trivalent
d_f vertices connected by three internally vertex-disjoint paths.
Leaves come only from B_out (3 of them) and the three non-bridge
triangle edges of O (the inner-triangle face boundary).
Adds experiments/draw_partial_tire_dual_bridge.py to generate the
figure.
Paper grows from 8 to 9 pages.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
didericis
7e4ccf2cc2