THE ELECTRONIC JOURNAL OF COMBINATORICS (ed. June 2005), DS #5. |
On the left: Grünbaum's coiled snakes. A k-fold 2-Venn diagram with mirror image symmetry. Shown with k = 4. Other values of k may be obtained by twisting/untwisting the tails. |
Grünbaum's rotated F's. A (2k+1)-fold 2-Venn diagram with rotational symmetry. Shown with k = 1. Additional twists of both ends give larger values of k. | Another Grünbaum example. A 2k-fold 2-Venn diagram with rotational symmetry. Shown with k = 3. Additional twists/untwists of both ends give other values of k. Note that the curves passing through the red vertices do not meet transversally. |
THE ELECTRONIC JOURNAL OF COMBINATORICS (ed. June 2005), DS #5. |