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Ring & Ringframe
Bridge & Bridgeframe
Safety versus Speed


Fork & Forkframe

There's a major difference between the fork and the other two winning structures:
  • Although a fork requires at least twelve stones, twice the number for a ring, a frame takes less than half this number.
The example shows the same 5-stone frame twice. In Cup & Trap is shown why it is a frame: black can cut on f4, but doing so will push white straight into victory.

Black therefore should leave white alone. Let's assume he has a frame elsewhere on the board, of approximately equal speed, so that the game turns into a race. The question of course is:

Just exactly how fast is white?

The answer is: the number of moves needed to complete the fork, minus the number of black stones white can draw into the position with moves that

  • 1) add to the completion of the fork, and
  • 2) threaten a ring or bridge in less moves than the forkframe itself.
The sequence at the top shows one of the many scenarios to do it in 10. Black sente moves are indicated by the move counter, but do not appear on the board: they're supposed to take place elsewhere without influencing the situation at hand.
White makes 16 moves, 6 of which require a local answer because they constitute ring threats. Of course this is not the final  answer to the origial question: make white 7 a one point jump to k18, and white can run the 18-line in sente for quite a while.
This low route has a resource to do it in 9, as shown at the bottom. White makes 19 moves, 10 of which require a local answer because they constitute a ring- or bridge threat.

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This is exactly what the race stage is all about: the one extra tempo you can squeeze out of a position using tactical threats. Of course the bottom sequence may not be the final  answer to the origial question either.