Parallel ladder

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A laddering situation in which the attacker can make two ladders on top of each other.

Consider the following position with Blue to play.

abcdefghij12345678910

All of Red's pieces form a connected group. This group is connected to the top. At the bottom, Red has a second row ladder with no possible escape on the left. The potential escapes on the right are inadequate. For example, suppose Red ladders to f9. Then tries to escape with

5. h9 g9
6. h8 g8
7. h7 f7.
abcdefghij12345678910

Now Red's only reasonable try is 8.g7 f8. Now 9.g6 loses to 9...f5 and 9.h5 loses to the forcing sequence 9...g6 10.h6 h4 11.g5 f5. All the other escape attempts likewise fail. Is Red done for?

No! Red can create a sufficient escape by making use of a parallel ladder. In the original position Red plays 1.e7. How can Blue stop Red from connecting to the bottom? d9 lets Red two-chain from e7 to f8 connecting to the bottom; e9 and e10 allow d9 which is connected to the bottom and threatens to connect to Red's big group through c9 and e8; d10 loses to e8, f9 (forced), c10; hence, Blue is forced to play the parallel ladder move 1...e8. It is simplest for Red to repeat this and ladder to f7 forcing the 2...f8 response.

abcdefghij12345678910

Now Red now goes back to the second row ladder and tries to escape. What have we gained by preceding this with the parallel ladder moves? When trying to escape, the threat to connect to d7-e7-f7 is stronger than the previous weak threat to connect to d7. This extra threat will let us push our escape chain farther up the board and in this case, just far enough to win the game.

Red's winning sequence is long but rather simple because every one of Blue's replies is forced. As before, Red ladders to f9 and escapes with 7. h9. Play continues 7...g9 8.h8 g8 9.h7 g7 10.h6 g6 11.h5. Red is threatening to play g5 with the double winning threats f5 and f6. But if Blue blocks this, say with 11...g5, then Red continues 12.i3 i2 13.h3 h2 and 14.g3 completes the win.

It is possible to use this trick off from one row farther back; i.e. with ladders on row 3 and 5 but this occurs far less frequently and one has to examine some additional defensive possibilities. Consider the following position.

abcdefghij12345678910
WARNING: Invalid cell name: b9
WARNING: Invalid cell name: ed
WARNING: Invalid cell name: has
WARNING: Unrecognized token: just
WARNING: Unrecognized token: played
WARNING: Unrecognized token: trying
WARNING: Invalid cell name: the
WARNING: Unrecognized token: parallel
WARNING: Unrecognized token: ladder
WARNING: Unrecognized token: trick.
WARNING: Unrecognized token: With
WARNING: Invalid cell name: the
WARNING: Unrecognized token: closer
WARNING: Unrecognized token: ladder
WARNING: Invalid cell name: on
WARNING: Unrecognized token: [[Second
WARNING: Unrecognized token: row|row
WARNING: Unrecognized token: 2]]
WARNING: Invalid cell name: we
WARNING: Invalid cell name: saw
WARNING: Unrecognized token: that
WARNING: Invalid cell name: lue
WARNING: Invalid cell name: was
WARNING: Unrecognized token: forced
WARNING: Invalid cell name: to
WARNING: Unrecognized token: respond
WARNING: Unrecognized token: with
WARNING: Invalid cell name: the
WARNING: Unrecognized token: parallel
WARNING: Unrecognized token: ladder
WARNING: Invalid cell name: e7.
WARNING: Invalid cell name: ut
WARNING: Unrecognized token: here
WARNING: Invalid cell name: lue
WARNING: Invalid cell name: has
WARNING: Invalid cell name: two
WARNING: Unrecognized token: additional
WARNING: Unrecognized token: possibilities
WARNING: Invalid cell name: and
WARNING: Unrecognized token: (the
WARNING: Unrecognized token: only
WARNING: Unrecognized token: other
WARNING: Unrecognized token: possibility
WARNING: Unrecognized token: where
WARNING: Invalid cell name: ed
WARNING: Unrecognized token: doesn't
WARNING: Unrecognized token: have
WARNING: Invalid cell name: a
WARNING: Invalid cell name: way
WARNING: Invalid cell name: to
WARNING: Unrecognized token: force
WARNING: Invalid cell name: his
WARNING: Unrecognized token: group
WARNING: Invalid cell name: to
WARNING: Unrecognized token: connect
WARNING: Invalid cell name: to
WARNING: Invalid cell name: the
WARNING: Unrecognized token: [[Bottom
WARNING: Unrecognized token: edge|bottom]]
WARNING: Invalid cell name: is
WARNING: Unrecognized token: c10.
WARNING: Invalid cell name: ut
WARNING: Invalid cell name: ed
WARNING: Invalid cell name: can
WARNING: Unrecognized token: respond
WARNING: Unrecognized token: with
WARNING: Invalid cell name: and
WARNING: Invalid cell name: now
WARNING: Invalid cell name: lue
WARNING: Invalid cell name: has
WARNING: Unrecognized token: nothing
WARNING: Unrecognized token: better
WARNING: Unrecognized token: than
WARNING: Unrecognized token: g6).
WARNING: Unrecognized token: yields
WARNING: Invalid cell name: a
WARNING: Unrecognized token: second
WARNING: Invalid cell name: row
WARNING: Unrecognized token: ladder
WARNING: Unrecognized token: after
WARNING: Invalid cell name: d9.
WARNING: Unrecognized token: The
WARNING: Unrecognized token: also
WARNING: Unrecognized token: leads
WARNING: Invalid cell name: to
WARNING: Invalid cell name: a
WARNING: Unrecognized token: second
WARNING: Invalid cell name: row
WARNING: Unrecognized token: ladder
WARNING: Unrecognized token: after
WARNING: Invalid cell name: the
WARNING: Unrecognized token: likely
WARNING: Unrecognized token: (d9
WARNING: Invalid cell name: is
WARNING: Invalid cell name: met
WARNING: Invalid cell name: by
WARNING: Invalid cell name: e7)
WARNING: Unrecognized token: d10.
WARNING: Unrecognized token: In
WARNING: Invalid cell name: the
WARNING: Unrecognized token: latter
WARNING: Unrecognized token: case
WARNING: Invalid cell name: ed
WARNING: Unrecognized token: could
WARNING: Unrecognized token: again
WARNING: Invalid cell name: try
WARNING: Invalid cell name: the
WARNING: Unrecognized token: parallel
WARNING: Unrecognized token: ladder
WARNING: Unrecognized token: trick
WARNING: Invalid cell name: by
WARNING: Unrecognized token: playing
WARNING: Invalid cell name: g7.
WARNING: Unrecognized token: Of
WARNING: Unrecognized token: course
WARNING: Invalid cell name: the
WARNING: Unrecognized token: presence
WARNING: Invalid cell name: of
WARNING: Unrecognized token: other
WARNING: Unrecognized token: pieces
WARNING: Invalid cell name: in
WARNING: Invalid cell name: the
WARNING: Unrecognized token: area
WARNING: Invalid cell name: can
WARNING: Unrecognized token: change
WARNING: Invalid cell name: the
WARNING: Unrecognized token: possibilities.
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