Lab sample Mini Sudoku Level 4. Dimensions 6×6. Givens: 18. Pattern tag: row-scan heavy. Technique histogram: 18× Naked single.
Board spotlight: Most fills come from scanning rows and columns for cells where only one digit fits — classic naked-single territory. Region geometry (6 regions, 6 cells each) shapes which unit yields the next hidden single.
Observation set 1: coordinates R1C2=4, R2C4=4, R2C5=5, R2C6=1; technique classes Naked single, Naked single, Naked single, Naked single.
Observation set 2: coordinates R3C5=4, R3C6=2, R4C3=2, R2C3=6; technique classes Naked single, Naked single, Naked single, Naked single.
Observation set 3: coordinates R2C1=2, R3C3=3, R3C1=6, R5C4=2; technique classes Naked single, Naked single, Naked single, Naked single.
Observation set 4: coordinates R5C5=3, R5C1=1, R6C1=3, R6C3=4; technique classes Naked single, Naked single, Naked single, Naked single.
Observation set 5: coordinates R6C5=6, R6C6=5; technique classes Naked single, Naked single.
Mid-solve checkpoint: 9 cells remain after the first half of the chain. Row-scan heavy boards often accelerate once two or three regions close — watch for hidden singles in tight blocks.
Late game: final batches collapse quickly when rows and columns near completion. Every row, column, and region contains digits 1–6 with no repeats. Completed path: R1C2=4, R2C4=4, R2C5=5, R2C6=1, R3C5=4, R3C6=2, R4C3=2, R2C3=6, R2C1=2, R3C3=3, R3C1=6, R5C4=2, R5C5=3, R5C1=1, R6C1=3, R6C3=4, R6C5=6, R6C6=5.
Lab result: Row-scan heavy. Technique summary 18× Naked single. Coordinates R1C2=4, R2C4=4, R2C5=5, R2C6=1, R3C5=4, R3C6=2, R4C3=2, R2C3=6, R2C1=2, R3C3=3, R3C1=6, R5C4=2, R5C5=3, R5C1=1, R6C1=3, R6C3=4, R6C5=6, R6C6=5.