Grafite Sudoku
Sudoku techniques
Sudoku techniques are patterns of reasoning that come back again and again: once you know them, you spot them in any puzzle. Here are the most useful ones, from the simplest to the most advanced, each with a drawn example.
They are the same techniques taught in the Sudoku Academy of Grafite Sudoku, where every lesson happens on the grid, one step at a time, with exercises taken from real puzzles.
The hidden single in sudoku
What a hidden single is in sudoku and how to find it: a number with only one possible spot in a row, column or box. With a drawn example.
Locked candidates in sudoku
Locked candidates in sudoku explained with an example: if inside a box a number can only sit in one row, remove it from the rest of that row.
The hidden pair in sudoku
The hidden pair in sudoku: two numbers that have only the same two cells in a row, column or box. How to find it and what to remove.
The X-Wing in sudoku
The X-Wing sudoku technique, explained simply: a number with only two spots in two rows, in the same two columns. With a drawn example.
The XY-Wing in sudoku
The XY-Wing sudoku technique, step by step: three cells with two candidates each and a number to remove where both "wings" can see.
The skyscrapers puzzle (City)
The skyscrapers logic puzzle explained with an example: the rules, what the edge clues mean and first strategies. In Grafite Sudoku it is called City.