Definition
Logic grid
A logic grid is a table for recording which pairings are impossible, possible, or confirmed.
| Person | Cat | Dog | Fish |
|---|---|---|---|
| Ava | ✓ | × | × |
| Ben | × | × | ✓ |
| Chen | × | ✓ | × |
What it means
Put one category down the side and another across the top. Each clue lets you cross out a pairing that cannot work or confirm one that must work. Keep combining the clues until the choices fit together. A logic puzzle grid, also called a deduction grid, records the reasoning so you do not have to hold every possibility in your head.
Remember it
Clues shrink the choices until every item has one fit.
Example
Match Ava, Ben, and Chen to Cat, Dog, and Fish. Ben has Fish. Ava does not have Dog. Chen does not have Cat. In a one-to-one puzzle, Ben–Fish is confirmed; the remaining clues force Ava–Cat and Chen–Dog. Every other cell is crossed out.
Watch for
A blank table, or a grid whose row labels, column labels, and symbols are undefined, is not yet a logic-grid record of deductions.
Common mix-up
An X means “impossible,” not “not tried”; always read the grid’s symbol key.
Exact meaning
A logic grid is an ordered table that records deductions between named categories in a constraint puzzle. Each cell represents one possible pairing. When the puzzle specifies one-to-one matching, the completed grid has exactly one confirmed cell in each row and each column.