Diagram 175 shows Template A-5. Despite being a template on the fifth row, this template is too large to be a significant threat. Nonetheless, it does appear occasionally. More significantly, some of the tactics involved are important to know, being applicable in various situations that occur outside this template.
This one is rather complex to analyze. Diagram 176 shows six reductions to simpler templates. Note that the points , and are included in all six reductions. Therefore, responses are required to White intrusions in these three hexes.
Template A-4 reduction.
Template A-4 reduction.
Template B-4 reduction.
Template B-4 reduction.
Template A-3 reduction.
Template B-3 reduction.
Template A-5 reductions. These overlap at points , and .
We begin with the intrusion at (Diagram 177). Black’s response is simple: he bridges to the right with , threatening to connect after another bridge to the right with Template A-3. White blocks with , resulting in a ladder. Black then plays a ladder-escape fork with , connecting either via the ladder or a double bridge. Convince yourself that White has no alternatives to .
Next up, intrusions at and . The response here is compact enough that we can use it for both if we just mirror the moves, so we only need to discuss one of these intrusions. Diagram 178 shows Black’s response to an intrusion at . After , Black threatens to either connect directly with a bridge at , or to play at and connect with Template D-4. White is forced to block at , the point where these threats overlap. Diagram 179 shows how Black uses a series of forcing moves to connect after the block by White.
Diagram 180 shows the two-stone, fifth-row template, Template C-5:
This template takes up significantly less room and can be very threatening. There are four basic reductions (Diagram 181), each of which uses a bridge plus either Template A-3 or Template B-3.
Template C-5 reductions, using Template A-3 (left) and Template B-3 (right). These reductions overlap at points and .
There are two intrusion points common to all these reductions. The responses to these intrusion points are detailed in Diagram 182. Note the similarities to Template C-4.
Consider the position in Diagram 183. The white stone is connected to the northeast with Template A-4, and a ladder is about to form on the b-file. But cannot serve as a second-row ladder escape, so how is White to win?
Even though can’t serve as second-row ladder escape, White can still use it to win the game. First she runs the ladder up the edge and then breaks with b2 (Diagram 184).
After the forced response b3 White can now run a “ladder” back in the opposite direction, with each move a forcing move, finally connecting at d5 (Diagram 185). This technique is called a switchback. Notice how each White move of the final sequence threatens to connect to White’s second-row stones, making Black’s responses forced.
A fourth-row stone can also switchback a third-row ladder. We can see the approach in Diagram 186, with Black using Template A-3. The resulting switchback returns along the fifth row.
Note that if White yields the third-row ladder to the second row, Black can use the second-to-fourth-row switchback, as in Diagram 187, to connect back to the initial stone.
In Diagram 98 we saw that a3 (or its equivalents) can’t serve as a third-row ladder escape. It can, however, be used to start a switchback. In Diagram 188 we can see that White has forced a third-row ladder along the northeast edge. This group is connected to the southwest edge through bridges to (which itself is connected by Template A-3). Notice how on k13 for White is equivalent to a3 for Black in Diagram 98. Notice also that at no point could Black yield the ladder to the second row because is a second-row ladder escape.
From this position White can start the switchback. White starts with j12 (Diagram 189). The k13–j12 group is connected to the northeast ( Template M-4a). After k10 White gets the switchback and goes on to finish the game: i11 j10 i10 j9 i9 j8 h8, and White is connected by either or . Had Black played k11, White first secures a second-row ladder escape before beginning the switchback with l10 k10 i11 etc.
It’s important to note here how critical the timing is. White needs to play no earlier or later in the ladder sequence, or else it won’t work.
Not all switchbacks will eventually reconnect so easily as seen in these examples. Nevertheless, they can often result in a long line of stones parallel to your edge which are connected to it. This effectively gives you a new “edge” closer to the center of the board, which is easier to connect to.
In some cases one ladder will fold under another. In Diagram 190, Black can ladder along the fourth row to the right. can’t escape a fourth-row ladder, but it can escape a ladder on the second or third row, so White cannot yield.
Nonetheless, Black proceeds (Diagram 191). After i10, Black’s combined threats (, with Template A-3, and with Template B-3) will force White to block at , the only point where all three threats overlap.
After the block, Black can squeeze through the bottleneck and play a second-row ladder towards the escape at , folding under the fourth-row ladder (Diagram 192).
Naturally, this can only occur with ladders on the fourth or higher rows.
It’s very important to understand how a stone on the fifth row can be used to escape second- and third-row ladders. Along the southeast of the board, j9 is the closest to the acute corner a black stone on the fifth row can lie and still serve as a second-row ladder escape. Along the other edges, d5 plays an equivalent role for Black, as do i10 and e4 for White. These moves are popular during the game’s opening phase.
Diagram 193 shows a black stone on j9 with a second-row ladder and the minimal ladder escape shaded.
Black approaches j9 with the sequence in Diagram 194, jumping twice. Note that moves and are not frequently played, however I’ve included them to show that Black still connects even if they are. From this position Black threatens to play either Template A-3 (Diagram 195a) or Template A-4 (Diagram 195b) on his tenth move. Black’s threats overlap at the six points labeled A–F so White will need to play at one of these for her ninth move.
Black’s threats for move 10. White will have to play move 9 at one of the labeled hexes.
Black’s responses are shown in Diagram 196. Diagram 196g shows Black’s response if White attempts to intrude into the bridge on move 5. It may seem difficult to remember seven different lines, but line (a) involves a common ladder-escape fork which any experienced player should be able to recognize, and there is a common theme running through lines (c), (d), (f) and (g). Each of these involves placing a stone on the 12th row connected to the bottom of the board, and then using a series of forced moves to go over and around it.
(a) ladder-escape fork.
(b) Trapezoid and Template A-3.
(c) Template A-3.
(d) Forced move sequence.
(e) Fork. Black plays either i12 or k10.
(f) Forced move sequence.
(g) Alternative move 5 by White. Black uses a forced move sequence.
Responses to White’s attempts to block.
Next we consider the third-row ladder. The first thing to note here is that f10 is part of the ladder-escape template for third-row ladders, and must be unoccupied by White. Now, if White never yields, the ladder will eventually reach f11 as in Diagram 197, and from this point Black’s approach will be identical to that of Diagram 194. White may attempt to yield the ladder to the second row instead. However, should she yield to d13 (or earlier) Black can respond with d12 c13 f11 and the situation will again be that of Diagram 194. Therefore the only new consideration for the third-row ladder is that of White yielding to e13 (Diagram 198). We can see Black’s response in the diagram, using Template A-4. Note how Black requires f10 here. If f10 isn’t free, this is the approach White should use to block.
Consider the situation in Diagram 199 with Black to move. Clearly Black can start a second-row ladder. But the threat of this second-row ladder allows Black to push a fourth-row ladder from which White cannot yield (Diagram 200). Black can push this ladder as far as he likes.
Why can’t White yield here? Because if she does, Black can create a ladder escape for the second-row ladder by intruding into the bridge as in Diagram 201.
This opens up tactical possibilities. There are many variations possible. In Diagram 202 Black makes use of the parallel ladder approach to play the ladder-escape fork , connecting by the ladder or the bridge.
In Diagram 203 (adapted from a real game) it is White’s turn to move. The – group is connected to the southwest via , and is also connected to by a Parallelogram. White needs to connect to the northeast. How should she proceed?
White begins with j7 k7 k6 m5 l6 m6 (Diagram 204). Now she plays what has come to be known as “Tom’s move” (evidently discovered by someone named Tom): k9. This move threatens to escape the second-row ladder, but if Black blocks the ladder at l7 White responds with j8 connecting anyway. Black’s only reasonable response here is l8 (m7 can be defeated with l8, as can anything further down, such as l9 l8). White now finishes the job with l7 m7 j10: the – group is connected to the northeast by Template E-4, and is connected to by either i9 (double bridge) or k8. Seeing that these threats don’t overlap, Black resigns.
Diagram 205 shows what is required to execute Tom’s move. We need the two connected stones and enough empty space to complete the move. Since the area is rather large, it is helpful to count out four bridge moves from the fourth-row stone as in the diagram.
There are many ways to get the two stones on the left, some of these are shown in Diagram 206.
Some approaches to Tom’s move.
Tom’s move gives rise to Template H-4, shown in Diagram 207.
A lone stone on the fifth row can be used to obtain a second-to-fourth-row switchback. Diagram 208 shows the approach. is connected to the bottom with Template D-4.
This same fifth-row stone can also be used to obtain a third-to-fifth-row switchback. If White doesn’t yield the ladder, Black’s approach is straightforward, as in Diagram 209. But if White attempts to yield to the second row, things go much worse for her: Black can apply the above second-to-fourth-row switchback to connect, as in Diagram 210.
Let’s see this put to use in an actual game. In Diagram 211 Black’s central group cannot be stopped from connecting to the northwest. But what about the southeast? Black can use to get a switchback and win. Black starts a ladder with c12 c13 d12 d13 and jumps to the third row with f11 (Diagram 212). White cannot yield the third-row ladder as discussed above. Black breaks the third-row ladder a few moves later with j11. After i11, Black begins the switchback and jumps again on move 17: j9 i10 i9 h10 h8. Now Black has a double threat and White is finished.
As a result of the above discussion, structures with two stones on the fifth row, like the one shown in Diagram 213, can be very powerful. The two stones can be any distance apart as long as there are at least two empty hexes between them. If either of these stones is connected to the other side of the board, it can be connected to the bottom using the techniques described in this section.
For example, say White attempts to block the left stone from the bottom. The result of such a block would be a second- or third-row ladder, and Black can use the other stone to get a switchback and connect. Diagram 214 shows an example with a third-row ladder. Try it yourself with a second-row ladder (White making two adjacent blocks at the start of the sequence).
Should White attempt a near block, Black can connect as in Diagram 215.
Although either of the two stones can connect to the bottom by using the other, this doesn’t necessarily mean that both can be considered to be connected to the bottom at the same time. Depending on the particulars, such as how far apart the two stones are and the presence of empty nearby hexes, it may be possible for White to play in the middle and force Black to connect only one of the two stones while cutting off the other. In practice, however, this tends to be difficult and leaves Black with plenty of opportunities for minmaxing replies.
As we saw above, j9 can escape second- and third-row ladders. How about fourth-row ladders? j9 can’t escape these ladders, but the situation is very favourable to Black.
White can’t yield the ladder to a lower row, or Black can use the escapes described above. She also cannot simply push the ladder. If she does so, Black will connect with Template A-4 as in Diagram 216.
Instead, White can step ahead one hex (Diagram 217). Black won’t be able to escape the ladder, however he will be able to fold under and get a second-row ladder heading back the other way.
Black can also switchback to the sixth row. Continuing from the position in Diagram 217, Diagram 218 shows how Black executes the switchback. Note that j9 is connected to the bottom: i11 k10 (with Template D-4).
Diagram 219 shows two other blocks by White. In both cases the outcome is the same: Black can fold under the ladder, as well as switchback to the sixth row. I’ll leave it as an exercise to figure out how.
I don’t recommend you memorize all these sequences—I certainly don’t! What’s important to remember is the outcome: that Black can fold under or get a fourth-to-sixth-row switchback (or both). This is what’s relevant strategically. The actual sequences can be worked out when the situation arises.
Parallel ladders, breaks and switchbacks can be combined in various ways to “climb” upwards. There are nearly unlimited varieties possible, but the basic idea is to break a ladder on the second or third row and, through a series of threats, connect to a group many rows back. Switchbacks and parallel ladders are used to create double threats which allow subsequent steps further back from the edge. A successful climb can take every trick at your disposal to execute. We’ll start simple and look at progressively more complex scenarios.
Diagram 220 shows an example of a basic climb (in fact this is an alternative approach to Diagram 107, back in 3.7 Advanced ladder handling). Black breaks the second row ladder with (Diagram 220a). After the forced reply , threatens to connect to via a double bridge (Diagram 220a), or to switchback along the fourth row (Diagram 220b), so constitutes a double threat.
Alternative climbing approach to Diagram 107.
Diagram 221 shows another example. After a8, we have a bottleneck formation. White starts by playing out one step of a parallel ladder with d5 c5. From here White can begin climbing. She starts with a second-row ladder escape (b4) forcing the response b5. d3 likewise forces the response d4. Now White can connect to with f2.
Alternatively, White could have used the switchback approach as in the previous example with b7 a7 b6 a6 b4 b5 d3 d4 f2. Sometimes you have a choice between the switchback approach and the parallel ladder approach, as in this example. Sometimes only one of these approaches will work, as in Diagram 220 where only the switchback threat was possible. Next we’ll look at an example where only the parallel approach can be used.
Diagram 222 shows our next climbing example. In this example it is critical that Black plays a parallel ladder rather than a switchback. After h1, we have a bottleneck, which will lead to a second row ladder. Black plays out the parallel ladder with e4 e3 d4 d3, then begins climbing with c2 g2 b4 c4. Now he plays b5, threatening to connect to . This is why Black needed to play out the parallel ladder: this threat would not have been available using the switchback approach. After the forced response c5, Black completes the climb with a7, connecting to .
Sometimes you need both a parallel ladder and a switchback threat. In Diagram 223, we have a climb which takes several steps. After a12, White can force a second row ladder along the southwest edge. First she plays out a parallel ladder with d9 c9 d8 c8. Next she begins the climb with b7 b8 d6. The parallel ladder serves as a threat, necessitating d7, but White is not done with it yet. Next she plays f5. Now the parallel ladder is serving a second purpose as a switchback threat, for if h4, then f6 e7 f7. If Black blocks the switchback then h4 completes the climb.
You can climb from ladders on higher rows than the second, so long as you have a backup plan in case your opponent yields. In Diagram 224, White executes a climb from the third-row ladder. Should Black attempt the yield the ladder to the second row, as in Diagram 225, White can use an alternative approach (note here how forms a Trapezoid with and ). If Black yields earlier, White can jump back to the third row at the critical moment: m4 l4 m3 k6 l6 k8 and then proceed as in Diagram 224.
The presence of additional stones can complicate matters, requiring creative solutions. In Diagram 226, White uses to work around the two Black stones ( and ) and climb her way to .
Many climbs are set up by territory gained much earlier in the game—often through intrusions or minmaxing plays. If we look back at an earlier stage of the game in Diagram 226, shown in Diagram 227, we can see that was actually placed as a minmaxing response to a block by Black.