Welcome to Vaki Puzzles

Vaki puzzles are solved by completing the grid so that there are two symbols in each cell (most commonly a letter and a number), each letter and each number appears once in each column and once in each row, and each pair appears only once in the grid.
Vaki puzzles range from the small and easier (3x3) to the really quite large and very demanding (10x10 and bigger).
They are related to sudoku. Technically, sudoku are incomplete Latin squares (with a block constraint) while vaki puzzles are incomplete Graeco-Roman or Euler squares