TECHNIQUE 2 OF 4
Corners: separate a permanent disc from a risky approach
A corner, once legally occupied, cannot be captured back. Moves near an empty corner deserve attention because they can create a capture line that makes it available to the opponent.
The rule and its limit
The six-by-six board's corners are R1C1, R1C6, R6C1 and R6C6. A corner disc cannot lie between a future opposing placement and another opposing disc because there is no board square beyond it. A move near an empty corner is not automatically bad; inspect whether it actually creates a legal opponent corner move and what other consequences follow.
A common mistake
Treating every edge disc as permanent extends the corner argument too far. Conversely, refusing all squares next to corners without checking legal replies turns a useful warning into an unsupported rule.
PLAYABLE EXAMPLE 1
A stable corner is available
Violet to move. Which legal moves occupy a corner? Compare them with a non-corner capture and identify any corner replies you would give away.
Loading playable study…
Select a legal empty square. Violet (V) and Cream (C) are the two players. You control both sides here. Bracketed discs flip automatically; a player without a move passes automatically.
Keyboard: Tab to an enabled control, then press Enter or Space. The study starts from the diagram shown; reload can restore your own saved moves.
Try the task before inspecting the answer.
Compare the starting moves
Legal corner moves: R1C6. A corner cannot subsequently be bracketed, so the corner disc is stable. That fact alone does not prove a full-game win.
| First move | Immediate effect | Checked consequence |
|---|---|---|
| R1C4 | Flips 1: R2C4. | Opponent has 7 legal replies. |
| R1C6 | Flips 1: R2C5. | Opponent has 4 legal replies. |
| R2C3 | Flips 1: R3C3. | Opponent has 3 legal replies. |
| R3C1 | Flips 1: R4C2. | Opponent has 5 legal replies. |
| R3C5 | Flips 1: R4C4. | Opponent has 9 legal replies. |
| R4C1 | Flips 1: R4C2. | Opponent has 5 legal replies. |
| R4C5 | Flips 1: R4C4. | Opponent has 8 legal replies. |
| R5C2 | Flips 1: R4C2. | Opponent has 6 legal replies, including corner R6C1. |
| R5C4 | Flips 1: R4C4. | Opponent has 7 legal replies. |
| R6C5 | Flips 1: R6C4. | Opponent has 5 legal replies. |
PLAYABLE EXAMPLE 2
Compare a corner with a larger field
Violet to move. Which legal moves occupy a corner? Compare them with a non-corner capture and identify any corner replies you would give away.
Loading playable study…
Select a legal empty square. Violet (V) and Cream (C) are the two players. You control both sides here. Bracketed discs flip automatically; a player without a move passes automatically.
Keyboard: Tab to an enabled control, then press Enter or Space. The study starts from the diagram shown; reload can restore your own saved moves.
Try the task before inspecting the answer.
Compare the starting moves
Legal corner moves: R1C6. A corner cannot subsequently be bracketed, so the corner disc is stable. That fact alone does not prove a full-game win.
| First move | Immediate effect | Checked consequence |
|---|---|---|
| R1C6 | Flips 1: R2C5. | Opponent has 5 legal replies. |
| R2C1 | Flips 1: R3C2. | Opponent has 6 legal replies. |
| R2C3 | Flips 1: R3C3. | Opponent has 5 legal replies. |
| R3C1 | Flips 3: R3C2, R3C3, R4C2. | Opponent has 4 legal replies. |
| R3C5 | Flips 1: R4C4. | Opponent has 8 legal replies. |
| R3C6 | Flips 1: R2C5. | Opponent has 6 legal replies. |
| R4C1 | Flips 1: R4C2. | Opponent has 8 legal replies. |
| R4C5 | Flips 1: R4C4. | Opponent has 8 legal replies. |
| R5C1 | Flips 2: R4C2, R3C3. | Opponent has 7 legal replies. |
| R5C4 | Flips 1: R4C4. | Opponent has 8 legal replies. |
| R6C5 | Flips 1: R6C4. | Opponent has 6 legal replies. |
A legal capture can open the corner to the opponent
On the diagonal, R1C1 and R2C2 are empty, R3C3 is Cream, R4C4 is Violet and R5C5 is Cream. Consider a Violet placement at R2C2; the specified diagonal makes that move legal.
The tempting move
Treat the capture at R2C2 as harmless to R1C1 because Violet is taking a disc rather than placing in the corner.
Why it fails
The move flips R3C3 to Violet. Cream can then place at R1C1 and bracket the Violet run R2C2–R4C4 against Cream at R5C5, capturing that line and taking the corner.
What you can conclude
The move demonstrably gives Cream a legal corner reply. That is a concrete strategic cost, not proof by itself that the entire game is lost. Compare it with the other available moves.
Try the idea in another position
Violet legally occupies R1C1. Does that prove Violet will win? Can Cream later flip that corner using a horizontal, vertical or diagonal bracket?
Check your reasoning
It does not prove a win, because the final result depends on the whole board. Cream cannot flip that corner: no capture line can bracket it with board squares on both sides. Its neighbouring discs do not automatically receive the same protection.