Cages and sums

This page covers rules that fix the sum of a set of cells: cages (6.3) and sum rules (6.8).

6.3 cage

{"type": "cage", "sum": 15, "cells": ["r1c1", "r1c2", "r2c1"]}

• Digits in a cage never repeat. sum is optional (a cage without a sum is a no-repeat set with a cage outline).
• A sum over cells where repeats are allowed is a sum rule (6.8), not a cage.

6.8 sum

kind	Fields	Meaning
little_killer	side, cells (the diagonal, ordered from the clue), sum	The cells sum to sum. Repeats allowed. The diagonal is exactly the listed cells.
frame	side, cells (ordered from the clue), sum	The cells (usually the first 3 of a row or column) sum to sum.
group	cells, sum	Any cell set sums to sum; repeats allowed.
corner	cells (a 2×2 block), sum	The 4 cells around a corner sum to sum; repeats allowed.