QED Logic quod erat demonstrandum

An Easy 6×6 Puzzle Solved with Region Confinement in 7 Steps

6×6 · easy · 7 steps

Play this board yourself →
A
B
C
D
E
F
1
2
3
4
5
6
1×
×
2
×
×
3×
×
×
×
×
×
×
×
×
4
×
×
×
×
×
×
×
×
×
×
×
5
×
×
6
×
×
×
×

This 6×6 board rates as easy (difficulty score 423). Solving it from scratch takes 7 logical steps, using 4 techniques: Single cell, Row/column exclusion, Adjacency clear, Region confinement. Every step below is forced: nothing here is a guess.

  1. First, every open cell left in this region sits in row 6, so its marker has to land there; that clears every other open cell in the row.
  2. Next, place a marker at E5. Region has exactly one open cell left. Placing here clears the rest of row 5, column E, and its region. Placing here also clears its 3 touching neighbours.
  3. Then, place a marker at D3. Region has exactly one open cell left. Placing here clears the rest of row 3, column D, and its region. Placing here also clears its 2 touching neighbours.
  4. After that, place a marker at C1. Region has exactly one open cell left. Placing here clears the rest of row 1, column C, and its region. Placing here also clears its 1 touching neighbour.
  5. Now, place a marker at F2. Region has exactly one open cell left. Placing here clears the rest of row 2, column F, and its region.
  6. From there, place a marker at B6. Region has exactly one open cell left. Placing here clears the rest of row 6, column B, and its region.
  7. Finally, place a marker at A4. Region has exactly one open cell left.

The key move here was Region confinement. Once you can spot that, this board falls quickly. ∎