Mirrored from **Sudopedia**, the Free Sudoku Reference Guide

# Mathematically equivalent

Two Sudoku puzzles are **mathematically equivalent** if one can transform the first into the second via a series of zero or more operations, where the allowed operations are:

- Relabel the 9 digits
- Swap any 2 rows in a floor
- Swap any 2 columns in a tower
- Swap any 2 floors
- Swap any 2 towers
- Swap rows with columns (i.e. matrix transpose operation)

In other words, two Sudoku puzzles are **mathematically equivalent** if they have the same canonical form.

If a puzzle **P** can be solved using a set of solving techniques, then any puzzle that is mathematically equivalent to **P** can also be solved using the same set of solving techniques. However, Sudoku Programs may rate two mathematically equivalent puzzles slightly differently because a different solving path is used. When a program checks for patterns one digit at a time, relabeling the digits may cause the solver to find patterns of similar nature in a different order.

A symmetrical puzzle can be mathematically equivalent to an asymmetrical puzzle. From an aesthetic point of view, these puzzles are completely different.

## See Also

This page was last modified 12:05, 17 November 2006.