Flat Mates
Every occurrence of the marked digit has the stated above digit immediately above it, or the stated below digit immediately below it.
Parameters
| Parameter | Meaning | Default |
|---|---|---|
| digit | The specified digit. | Required. |
| above | The digit immediately above the marked digit. | Required. |
| below | The digit immediately below the marked digit. | Required. |
Maths
Class: first-order.
The shared predicates define the notation and every named predicate.
∀c ∈ C: D(c)=digit → ∃a ∈ C: (aboveCell(a,c) ∧ D(a)=above) ∨ (aboveCell(c,a) ∧ D(a)=below)
Every occurrence of digit has above immediately above it or below immediately below it (or both). An out-of-board neighbour cannot satisfy the condition.
Example
---
format: open-rules
title: Flat Mates example
setter: Example
source: ""
case: ""
library: https://rules.sudoku-sleuth.com/
status: read
---
```rules
sudoku 9x9
flat-mates digit 5 above 1 below 9
```
Satisfies the rule: r1c1=1, r2c1=5, r3c1=1. The marked 5 has the required 1 directly above it.
Breaks the rule: r1c1=5, r2c1=1, r3c1=1. The marked 5 is on the top edge and lacks its required neighbour below.