# Scaled Polyomino Tetrads

## Introduction

In plane geometry, a *tetrad* is an arrangement of four congruent
shapes in which each borders the other three.
See Polyform Tetrads.
At his website Atlantis, Dr. Karl Scherer introduced *similar*
or *scaled tetrads.*
These are arrangements of four geometrically *similar*
figures in which each borders the other three.
That is, they have the same shapes but not the same sizes.
In general, scaled tetrads are easier to find that standard tetrads.

No rectangle can form a tetrad, with or without scaling.
Here I show the smallest known scaled
tetrads for non-rectangular polyominoes with from 3 to 6 cells.
For each such polyomino I show a holeless tetrad if I know of one.
Otherwise I show a tetrad with holes.
If you find a holeless tetrad for a polyomino that was not known
to have one, please write.

## Tromino

## Tetrominoes

## Pentominoes

## Hexominoes

Last revised 2022-03-29.

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Col. George Sicherman
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