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Lines and arrows

This page covers rules drawn along a path of cells: lines (6.4) and arrows (6.5).

6.4 line​

{"type": "line", "kind": "thermo", "cells": ["r5c3", "r4c3", "r3c3", "r3c4"]}
{"type": "line", "kind": "whisper", "value": 5, "cells": ["r7c7", "r7c8", "r8c8"]}
{"type": "line", "kind": "renban", "closed": true, "cells": ["r2c2", "r2c3", "r3c3", "r3c2"]}

Common fields: cells (ordered, at least 2) and closed (default false): a loop, the last cell connects back to the first. closed is allowed only for whisper, renban and parity.

kindParametersMeaningDrawing
thermo–Strictly increasing from cells[0] (the bulb). Branching thermos are separate rules sharing cells[0].
slow_thermo–Non-decreasing from cells[0].
whispervalue k (1..D−1): REQUIRED when D ≠ 9; default 5Adjacent cells on the line differ by at least k (German whisper = 5, Dutch = 4).
renban–The cells hold a set of consecutive digits, no repeats, any order.
region_sum–Split the line into segments wherever it passes from one box to another; every segment has the same sum. Boxes are those of box_grid and box rules (jigsaw pieces included); extra regions, windows and diagonals do not split the line.
palindrome–Reads the same from both ends.
entropicgroups: REQUIRED when D ≠ 9; default [[1,2,3],[4,5,6],[7,8,9]]Every run of 3 consecutive cells holds one digit from each group.
modularvalue m (≥ 2): REQUIRED when D ≠ 9; default 3Every run of m consecutive cells holds one digit of each residue class mod m.
parity–Adjacent cells on the line differ in parity (alternate odd / even).
zipper–Cells equally far from the centre of the line sum to the same total (the centre digit, for an odd length).
between–Digits strictly between those of the two ends cells[0] and cells[-1], ends in either order.
lockoutvalue k (1..D−1): REQUIRED when D ≠ 9; default 4The ends differ by at least k; every other digit lies outside the closed range of the ends.
double_arrow–The two ends sum to the total of the cells between them.

Repeats: allowed on every line (subject to houses), except renban.

6.5 arrow​

{"type": "arrow", "bulb": ["r2c2"], "lines": [["r3c3", "r4c4", "r5c5"]]}
{"type": "arrow", "bulb": ["r1c1", "r1c2"], "lines": [["r2c3", "r3c3"], ["r2c1", "r3c1", "r4c1"]]}
  • bulb: 1 or more orthogonally connected cells, read as one number in bulb order (a pill [a, b] is 10·a + b).
  • lines: 1 or more shafts, each ordered away from the bulb; the first cell of each shaft touches a bulb cell.
  • Each shaft's digits sum to the bulb number. Repeats allowed.