How these are built
A harder logic puzzle has fewer clues, not more
That is the opposite of what most people expect, and it is measured rather than asserted. An Easy puzzle here averages 12.0 clues and an Expert one averages 8.3. Difficulty is not how much you are told. It is how far you have to carry it.
Every clue on the sheet is load-bearing
The most common failing of a generated logic puzzle is a clue list padded with statements nobody needs. They are true, they are cheap to produce, and they turn a deduction into a search. This generator builds a large pool of true clues, adds from it until the puzzle can be solved, and then takes clues away again for as long as it still solves. What is left cannot be reduced: remove any single clue from any sheet this page prints and the puzzle stops being solvable.
Each level is named after the deduction it forces
A puzzle is only offered at a level once the generator has confirmed it cannot be finished without that level's step, and confirmed that it can be finished with it. Every sheet is also checked against an independent search that uses no technique at all, which confirms exactly one arrangement fits the clues.
| Level | The step it forces | What that means at the table | Clues |
|---|---|---|---|
| Easy | One square left in a row or column | When a row or a column has only one square left uncrossed, that pairing is the answer, and the rest of its row and column can be crossed out. | 12.0 |
| Medium | Carrying a fact through a third category | The step that needs the grid. If Ruth did not bake the ginger loaf, and the ginger loaf came third, then Ruth did not come third. That fact is now on the grid and nobody wrote it. | 9.7 |
| Hard | Arithmetic on the ordered column | On the ordered column, "two places ahead" rules out both ends. If someone finished two places ahead of somebody else, neither of them can be in the last two positions or the first two. | 7.3 |
| Expert | Following a pairing until it breaks | Pencil in a pairing, follow it with the rules above, and if the grid breaks then the pairing was impossible. This is proof rather than guessing: the wrong branch is ruled out, not abandoned. | 8.3 |
Levels and clue counts are read from the engine at build time. Each row names the step the sample puzzle for that level actually required.
The levels differ in what the clues look like, not only in how hard they are
An Easy sheet contains no clue that links two attributes without naming a person, and no arithmetic at all: every clue is of the form "Ruth did not bake the ginger loaf". Medium adds clues like "the ginger loaf baker finished third", which cannot be written into a single square and have to be carried across the grid. Hard and Expert add comparatives on the ordered column. You can tell the level of a sheet by reading its clue list, before solving a single square.
The grid on the page has blocks the solver does not need
The printed grid is a staircase: the people against every attribute, then the attributes against each other. That second part is what makes the puzzle solvable by hand, because a person cannot hold "whoever owns the collie also drinks tea" in their head across six categories. They need somewhere to write it.
The solver inside this page does not have those blocks at all. It keeps everything against the people and derives the rest, which is faster and completely useless to a human. The tool and the paper need different shapes for the same puzzle, and the drawing code is where that difference is handled rather than being smuggled into the engine.
How to start one, if you never have
- Read every clue and mark the ones that name two specific things. Those go straight on the grid as a tick or a cross.
- Every tick lets you cross out the rest of its row and the rest of its column, because nothing is shared.
- When a row or column has one square left, that square is a tick. Mark it and repeat step two.
- Now carry facts sideways: if Ruth is not the ginger loaf baker, and the ginger loaf baker came third, then Ruth did not come third.
- Go back to the clues you could not use yet. They usually work once a few squares are filled.
What this page does not do
The scenarios are written by hand and there are 8 of them, so a visitor who prints a great many packs will start to recognise the premises even though the arrangements and clues are always new. Adding more is writing rather than coding.
Puzzles are four or five people with three attributes each. Six-category puzzles, the kind that fill a page of a magazine, need a larger grid than fits comfortably on one sheet alongside its clues, and they are a different product rather than a bigger setting.
How this page is made and checked
Print Puzzles is part of the Hamilton Digital Media Limited puzzle network. This page is written and reviewed by Brian Hamilton and Karan Hamilton. The engine was checked with a build-time harness that generated puzzles at both sizes and all four levels and confirmed, for every one, that each clue is true of the answer, that each clue is a properly formed sentence, that no clue is repeated, that the logical solver reaches the answer exactly, that the puzzle cannot be solved one rung below its own level, that no clue can be removed, and that an independent exhaustive search finds exactly one arrangement. Read more about how we make puzzle packs, or tell us about a sheet that misbehaves through the contact page.
Nothing here costs anything and there is no account. Puzzles are generated in your own browser rather than fetched from a server, and the terms of use let teachers, tutors, clubs and families print and copy these sheets and their answer keys freely.