Baiocchi Figures for Diaboloiamonds

Introduction

An aboloiamond is a plane figure made by joining an equilateral triangle to a leg of an isosceles right triangle:

Its interior angles are 45°, 105°, 60°, and 150°. As far as I know, it first appeared in Michael Goldberg's article Central Tessellations in volume 21 of Scripta Mathematica in 1955.

The term aboloiamond (abolo + iamond) is due to Masayoshi Iwai. He designed a puzzle called Aboloiamond 48, consisting of 48 aboloiamonds in a dodecagonal tray.

A diaboloiamond is a polyform formed by joining two aboloiamonds at equal edges. There are 14 diaboloiamonds, identifying mirror images:

A Baiocchi Figure for a polyform P is a polyform made by joining copies of P and having the maximum symmetry for that class of polyforms. For polyaboloiamonds this is 12-fold rotary symmetry with reflection.

Here I show a minimal known Baiocchi Figure, if any, for each diaboloiamond.

I am grateful to Irmtraud Beyer for telling me about the history of aboloiamonds.

6 Tiles

12 Tiles

24 Tiles

48 Tiles

Unsolved

Impossible

Last revised 2025-10-15.


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Col. George Sicherman [ HOME | MAIL ]