## What is this technique called?

Advanced methods and approaches for solving Sudoku puzzles

### What is this technique called?

I just learned how to play sudoku 2 or 3 weeks ago. All I learned was that no digit can repeat in a box, row, or column, and I pretty much just taught myself from there. I looked up Swordfish, X-Wing, and Y-Wing about a week later, but I had already figured out Swordfish and X-Wing on my own, so Y-Wing is really all I learned from someone else, and I haven't had a chance to use it yet. I now came up with a new technique and I am wondering if other people use it, and if so, what it is called. R3C9 has to be 5 because R1C1, R3C1, and R1C9 are each 7 or 8, and R3C9 can be 5, 7, or 8. If it is not 5, then there are two solutions to the puzzle, because it leaves 4 corners of a rectangle each with the same two possible numbers, and as far as I know a puzzle can only have one solution. Thanks.
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### Re: What is this technique called?

Unique rectangle.

JasonLion
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