Counting Circles

Each digit appearing in the circles tells you how many circles contain that digit.

Parameters

Maths

Class: with aggregates.

The shared predicates define the notation and every named predicate.

∀d∈faceDigits(cells): countWhere(cells,λc:cell: D(c)=d)=d

Each digit occurring in cells occurs exactly as many times as its digit.

Example

---
format: open-rules
title: Counting Circles example
setter: Example
source: ""
case: ""
library: https://rules.sudoku-sleuth.com/
status: read
---

```rules
sudoku 9x9
counting-circles r1c1-r1c2-r1c3
```

Satisfies the rule: r1c1=1, r1c2=2, r1c3=2. 1 appears once and 2 appears twice.

Breaks the rule: r1c1=1, r1c2=2, r1c3=3. 2 and 3 each appear only once.