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Tap a cell to cycle blank → ✗ → ✓ · placing a ✓ auto-crosses its row and column · prefer the full app experience? Open Game Hub →
Logic Grid puzzles present a small scenario — typically a handful of people, each with several attributes such as their job, their favourite colour, the pet they own, and the drink they prefer. Underneath the scenario sits a list of clues: "The doctor lives in the red house", "The cat owner drinks milk", "The teacher does not own a dog". Your task is to use those clues to deduce every attribute of every person.
The deduction grid is your tool. It's a cross-reference table that lets you mark which pairings are impossible (X) and which are confirmed (✓). As you process each clue, the grid fills up — and the structure of the puzzle forces conclusions you'd never see by trying to hold everything in your head.
Logic grid puzzles — sometimes called "Einstein puzzles" or "Zebra puzzles" — became famous because of a puzzle published in Life International magazine in 1962 that began "There are five houses in a row" and claimed only 2% of people could solve it. The puzzle is sometimes (incorrectly) attributed to Einstein. Logic grid puzzles are a recreational version of what computer scientists call constraint satisfaction problems — the same class solvers use for Sudoku, scheduling, and Boolean SAT.
You will not solve a non-trivial logic grid puzzle in your head. The deduction grid is not optional — it's the central tool. For every pair of attribute categories (people × pets, people × colours, pets × drinks, and so on), draw a small sub-grid and use it to record what's possible and what isn't.
The grid does the cognitive heavy lifting. Without it you'll keep forgetting which combinations have already been eliminated and re-deriving the same facts. With it, every clue you read instantly turns into a permanent mark, and the puzzle becomes a methodical sweep instead of a feat of memory.
Mark transitively: if you confirm that the doctor lives in the red house, you can put X on every other red-house combination (no one else lives in the red house) and on every other doctor combination (no one else is the doctor). One ✓ usually generates many X's.
Beginners only mark confirmations. Experts mark impossibilities first. Every clue tells you something is impossible somewhere — even clues that look weak. "The doctor is not the cat owner" adds a single X to the grid. "The teacher does not drink coffee" adds another. Individually they look small, but they chain together.
Don't wait for a clue to confirm something before you act on it. Process every clue for its X's the moment you read it. After all clues are processed for impossibilities, the confirmations often fall out automatically — a sub-grid row with X's in every cell except one means that one cell must be ✓.
A forced position is any cell that has to be ✓ because every other cell in its row or column is already X. After each clue, rescan every sub-grid for forced positions. You will frequently find that a clue you've just processed has indirectly forced a confirmation somewhere unexpected.
In a 4×4 puzzle, every row and every column of a sub-grid will eventually have exactly one ✓ and three X's. As soon as three X's appear in a row, the fourth cell is your next ✓ — no extra reasoning required. Chain these forced positions and large parts of the grid resolve themselves.
The hardest deductions in a logic grid come from combining two or three clues that none of them give on their own. Example: clue A says the cat owner drinks milk; clue B says the cat owner is not the doctor; clue C says the doctor lives in house 3. Individually each is weak; together they tell you the milk-drinker is not in house 3.
When you're stuck after applying every clue once, slow down and re-read each clue while looking at the grid. Ask "what does this clue tell me given what I already know?" Often the clue you read in round one with no context becomes pivotal in round three when half the grid is filled in.
Desktop: Click a cell in the deduction grid to cycle it between blank, X (impossible) and ✓ (confirmed). Right-click cycles in the reverse direction. The clue list is always visible at the side or bottom of the puzzle.
Mobile / Tablet: Tap a cell to cycle through the three states. Long-press a cell to skip directly to ✓. The grid scales to fit your screen; landscape orientation works best on phones for larger puzzles.
The puzzle is solved automatically when every cell is determined — no need to press a "check" button.
Logic grid puzzles come in a wide range of sizes and shapes, each with its own difficulty curve. The MindArena hub mixes several variants so the challenge stays fresh:
Start with 4×4 puzzles to build the technique before tackling the classic 5×5 Einstein-style challenges.
A logic grid puzzle (also called a zebra puzzle or Einstein puzzle) presents a scenario with several people and several attributes — jobs, colours, pets, drinks — and a list of clues. Your task is to use the clues to deduce every attribute of every person. The deduction grid is a tool for tracking what you know and what's still possible.
Almost certainly not. The famous five-house puzzle is often credited to Einstein, but there is no evidence he wrote it. The earliest known version was published in Life International magazine in 1962 and claimed only 2% of people could solve it. The Einstein attribution appears to be folklore that grew up around the puzzle later.
Build a cross-reference grid for every pair of attribute categories. Read each clue and mark impossibilities with X and confirmed facts with a tick. When a row or column has X's in all but one cell, that remaining cell must be a tick. Chain implications across clues — most puzzles are solved by combining what two or three separate clues let you infer together.
A 4×4 puzzle — four people, four of each attribute — is the standard easy size. It's solvable in 10–15 minutes once you know the technique. The classic 5×5 Einstein puzzle is the next step up, and 6×6 puzzles are challenging even for experienced solvers.
Yes — every well-constructed logic grid puzzle has a unique solution reachable purely by deduction. If you find yourself guessing, it means you've missed a clue or a chain of implications. Re-read the clues carefully. Guessing is never required and usually leads to a dead end.
Both are constraint satisfaction problems — the same broad class of problem computer scientists solve with SAT solvers and constraint engines. Sudoku constrains digit placement by row, column and box. Logic grids constrain attribute pairings by the clues. The deductive techniques (marking impossibilities, chaining implications) are nearly identical.
Start with a 4×4 puzzle and put the cross-reference grid to work.
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