Glossary

Alternatives. Techniques that would each do the same job at a point of the solve. On the card they share a chip: XWG/KTE/SCL means an X-Wing, a 2-String Kite or simple colouring works there.

Band. What you need to know to solve the puzzle: Very Easy, Easy, Medium, Hard, Very Hard, Expert or Extreme. It is the band of the hardest technique on the route. See Philosophy.

Box. A block of cells that must hold every digit once, 3×3 on a classic. Boxes of other shapes are jigsaw boxes.

Candidate. A digit a cell can still hold. Writing candidates in the cells is taking pencil marks (notes).

Card. The result of grading a puzzle: band, difficulty, time, contains, and any fields asked for. Format: Grade card.

Chip. One entry of contains: a technique code, or several joined by / when they are alternatives.

Contains. The techniques the route needs, easiest first, singles included; the shortest list that still solves the puzzle.

Difficulty. How hard the steps are to find, on a scale from 0 with no ceiling; it does not grow with the size of the puzzle. See How a card is computed.

Given. A digit printed in the puzzle at the start.

Golden corpus. A fixed set of puzzles whose every output is recorded (tests/golden), so a change to the code can show exactly which outputs it moves. For contributors.

Grid. A square of cells with its own rows and columns; a multi-grid puzzle has several that overlap.

House. A set of cells that must hold different digits, usually every digit once: a row, a column, a box or an extra region.

Issues. Publishing checks on the card: a rule nobody needs, too many givens, most of the effort in a few steps. See Check a puzzle before publishing.

Layout. The arrangement of the grids of a multi-grid puzzle (Samurai, Twodoku, ...). See Variant catalogue.

Placement variant. A variant that adds fixed regions to a grid: X diagonals, Windoku windows, Argyle lines.

Region. A set of cells a rule talks about; an extra region is an extra house.

Route. The order of steps a person would take: at each point the easiest available technique. The band route sets the band and contains; the written route, without the steps people do in their head, is priced for difficulty and time.

Rule. One entry of a puzzle file's rules: the grid, a cage, a thermometer, a dot. A rule family is a kind of rule (all cages, all thermometers). See Rule families.

Single. The simplest placements: a hidden single (the only place for a digit in a house) or a naked single (the only digit left for a cell).

Spec. A request to the generator (sudoku-spec): the board, rule templates, and what the card must show. See Generator spec.

Step. One move of the route: a placement or some eliminations, made by one technique.

Technique. A named way of finding a step, such as X-Wing or Naked Pair. Each has a three-letter code, Andrew Stuart's where he has the strategy.

Template. A rule in a spec with a count and no cells: the generator places rules of that family.

Time. The predicted median solve time in minutes for the people who solve puzzles like it.

Variant. A sudoku with rules beyond rows, columns and boxes.