Move Debt - Scam Your Way to Victory

Author’s note: The “scam” and related terminology is meant to be tongue-in-cheek and evocative imagery for the DDKs - this article isn’t actually about cheating! The strategic concepts discussed within are both legitimate and serious.

High-level baduk is a scam

If you’re anything like me, during your days as a kyu player you’ve played your honest share of handicap games against low or mid-dan players. In a fair number of those games you probably felt pretty good throughout the opening and middlegame - hey, for once my groups aren’t dying all over the place! But you keep playing, you keep holding your own through all the fights - then all of a sudden it’s late middlegame/early yose and you wonder, where did my lead go? All your groups are safe, and you can’t really point out a local mistake, but what was once a 30-40 point lead from your handicap stones has magically dwindled to 10, within range of a dan player’s superior yose technique. During the review your opponent might tell you “this was bigger” or “this was slow,” but you still come away a bit nonplussed as to what they saw and why you didn’t.

Well, today in this article I’m going to reveal the dirty little secret: all dan players are scam artists. You lost not because you did anything egregiously wrong, but because your opponent cheated you - subtly, innocuously, and constantly. Nonsense, scoffs the DDK - there may be plenty of scummy stuff you can do over the board or online, but you can’t outright cheat in this game! But that’s the most insidious part - the scariest scams, both in real life and in baduk, are the ones that are technically legal, the best kind of legal. And although that means you can’t stop the scam, you know what they say: if you can’t beat’em, then join’em! In this article, we will introduce the concept of move debt and join in on the secret scam that is high-level baduk strategy.

What is move debt?

Move debt isn’t something with a precise definition written down somewhere - there isn’t even a Sensei’s Library article on it. However, it is something that high-level players will reference here and there, in terms such as “owing a move locally” and the like. We have done so ourselves multiple times in past articles on this blog. It’s something that is more easily recognized in play than defined in the abstract. But if we were to have a go at it, a very strict form of the definition would be something along the lines of the following:

Move debt occurs when an extra move needed to stabilize a local position is omitted.

The reason this is hard to define precisely is that “stabilize” can mean a lot of things in baduk, and the stability of a position is both a local and global issue. But move debt for the most part does pertain to local stability. Things like ladder considerations can affect it, but it’s convenient for our discussion to think of it as primarily a local issue.

When might move debt occur in practice? It turns out that move debt happens all the time, examples being:

1. Leaving a locally viable cut undefended.

2. Not extending from a group that otherwise has limited intrinsic eyespace.

3. Leaving a sizeable gap in a moyo that could potentially convert to territory with an extra move.

4. Enemy stones within your influence that are likely to die in theory, but could potentially have bad aji with nearby support.

This is not an exhaustive list. The commonality is that from a local perspective, the problems in these positions could be resolved or significantly alleviated with the addition of an extra friendly stone, such as defending the cut, extending from the group, reinforcing the moyo, or spending an extra move to subjugate the enemy stones. This is such a frequent scenario that ultimately, it’s easier to recognize move debt in a situation than to systematically list every way in which it can arise. Nor is all move debt the same: some debt is more severe than others. Let’s examine some examples to get an idea of what move debt looks like in practice.

Examples from jōseki

The simplest way move debt can arise is tenuki. Here White plays elsewhere after Black responds to its 4-4 low approach, incurring a move debt in the lower right. One easy (though not universal) way to detect move debt, especially in a jōseki context, is to compare the local tally. Here, by virtue of White playing elsewhere, White takes a deficit of -1 in the local tally in the lower right.

Because White has played elsewhere in a situation where White is normally expected to respond (from a purely local perspective - we’re not taking global considerations into account here), White has thus put itself into move debt: it owes Black a stone in the lower right. This move debt is outstanding until one of the two players returns to the corner. If White returns to the corner first, it can resolve its move debt and the local tally evens up again, as if White had never played elsewhere. But if Black returns to the corner first, then Black can collect on White’s debt by playing an extra stone to create a locally favorable situation; the diagram illustrates the two most common ways to do so.

Note that none of this discussion is about whether the outcome favors Black or White overall. Incurring move debt is not inherently a bad thing, nor is collecting on it inherently a good thing. This particular diagram is a perfect example: White’s tenuki after Black’s response to the low approach is a perfectly valid option that has become popular even among amateurs due to AI influence, implying that the situation does not necessarily favor Black globally even though White is obviously on the back foot locally. Playing around move debt is deeply intertwined with global strategy, but move debt by itself is fundamentally a local consideration.

In our next example we see how move debt naturally occurs multiple times during the development of a local position. The first notable move debt in this sequence occurs when Black plays elsewhere in response to White’s low approach. Black thus goes into debt in the bottom right, as it has omitted a local response to defend its corner, and potentially gives White a chance to shift the balance of power in this corner from Black-favored (by virtue of having the corner) to White-favored (by virtue of an extra stone). Assuming the situation elsewhere ends in White sente, White returns to the bottom right to collect on Black’s debt, namely by entering the double low approach.

The next notable move debt occurs at the breakpoint in this line of the double low approach. White’s next local continuation is typically to reinforce one of its two groups: either choice is viable, and the decision comes down to direction of play. But since White can only play one side at a time, this time White enters a local tally deficit, and hence move debt, on whichever side White fails to reinforce. Black can then call on White’s debt by attacking the weaker side. Black also owes White a move locally, as it has an exposed cutting point that White could threaten given the proper support. The continuations from this jōseki, as well as its evaluation, revolve around how well each side can play around each others’ debts.

Examples from fuseki

Here is a simple fuseki example of move debt. Black has played a very typical sanrensei opening, and after 1 it owes moves in multiple locations, not all of which are depicted. The most significant one is A: the jōseki in the bottom right is incomplete according to classical theory, as it leaves behind a cutting point. This is not necessarily a bad thing: approaching the top right corner is big too, and it is valid for Black to consider it worth it to approach at the cost of incurring the debt at A. There is also a debt at B because there is a cut available to White which can be dangerous for Black if White gets support; White could collect on this debt by approaching along the left side. Black also owes a move at C, which will determine how much of the bottom side Black can claim.

An important takeaway from this position is that move debt is not synonymous with deficits in local tally. Local tally is most useful as an indicator of move debt in joseki analysis, but move debt can be discussed in a broader context than just joseki. Here, although the local tally in the bottom right is even, Black does have a type of move debt in the sense that it has omitted a fairly standard defense of the major cutting point at A. Again, this is not about whether the outcome favors Black or White overall; indeed, modern sanrensei theory suggests that defending the cut is slow. We are simply noting that Black has left a weakness undefended (even if intentionally), and thus White may have an opportunity to extract value from this omission.

Even the fact that Black owes multiple moves on the board does not mean that Black is in a bad position. Although we have phrased the situation as Black owing White multiple moves, that is not to say that Black should play those moves. An observation of move debt is merely an observation of a local deficiency, not a recommendation of a move to play. Indeed, right now the best moves for Black are probably near the top side or White’s two top corners. Both White and Black will look to play around Black’s debts: Black to ameliorate their negative consequences, and White to exacerbate them, but this does not necessarily involve addressing them directly. For instance, White could use the weakness at A to threaten a sente exchange in support an invasion or reduction of Black’s center.

Dancing on a knife’s edge

As is hopefully clear from these examples, move debt is a fairly general phenomenon which is 1) closely related to many concepts such as group strength and shape, and 2) unavoidable in normal play. It is no exaggeration to say that baduk gameplay, to a large extent, consists of playing around move debt. Here are the general principles one needs to know about move debt:

Incurring move debt is not a bad thing: it most commonly occurs as a consequence of efficient/fast play.

Recall that in our definition, move debt is primarily a local concern. Move debt generally does not occur if you immediately defend all of your cutting points, extend conservatively from all of your weak groups, add stones to convert your moyo to territory, et cetera. But such moves are generally signs of slow play. Move debt occurs naturally in efficient play: playing lightly, making wide extensions, and tenuki are all examples of moves that incur move debt by definition.

Not all move debt is created equal, and too much move debt is potentially a bad thing.

Some weaknesses can be left undefended for a time (or even permanently), which constitute move debt which is not too severe. But of course, some weaknesses have to be defended right away: neglecting them constitutes incurring a severe move debt which may be collected on immediately. Although some move debt is a sign of efficient play, too much move debt or overly severe move debt is a sign of playing too thinly or carelessly.

Ultimately, every baduk player needs to strike a delicate balance when managing their move debt. You must incur some move debt if you are to play efficiently, but if you overdo it then your position will collapse under pressure. Of course, none of this is news to anybody: we are merely stating the idea that baduk requires a balance between thinness and thickness in new terms.

The move debt scam

So how does this all relate to dan players being a bunch of dirty cheaters? The basic idea is that strong players incur lots of debts during the game, but they hate paying them back. They’ll make every effort possible to avoid paying their move debts without being punished for it. If baduk were real life, dan players would be the ones running up thousands in credit card debt and then running from their creditors. In the meantime, dan players are also loan sharks: they’ll do everything in their power to collect on their opponent’s move debts, and to hell with hypocrisy.

The 3-step guide to being a debt scammer

1. Rack up a bunch of debts.
2. Avoid paying your debts whenever possible.
3. Force everyone else to pay their debts.

But how does one avoid paying their debts? The key is that move debt is about the omission of a local move, but move debt need not be resolved locally. In many cases, it is possible to create a global board-state in which the need for an extra stone in the local position disappears. In that case, the stone that was supposed to be used to pay off the move debt locally can be put to better use elsewhere. Essentially, the move debt scam consists of moving stones that should have been played locally to anywhere you like on the board. In addition, one can find efficient local ways to address existing debts; for example, this is the purpose behind many shape tesuji.

This is key to how strong players beat weaker players in handicap games. The difference between strong and weak players is that strong players avoid paying debts that don’t need to be paid, and pay the only ones that do: weak players pay debts that don’t need to be paid, and fail to pay debts that must be paid. A sufficiently strong player can win (whether handicap or even) without coming out massively ahead on fighting by building more efficiently, which consists of finding opportunities to omit as many moves as they can afford to while building: each of those omitted stones represent additional value when played elsewhere. At the same time, they will force the opponent into playing the moves they are owed locally, in essence preventing those stones being played in more gainful locations.

Examples from jōseki and fuseki

In the first example, we examine a common situation in the low Chinese fuseki. The key thing to note about Black’s descent is that Black owes White a move locally due to some bad aji in the descent variation of this jōseki if White chooses to clamp; this aji also makes an approach from the side potentially sente against Black’s group. However, to defend against the clamp immediately would be slow.

Black gets around this by using the weakness of the White group. Due to the descent and the Black stone on the side, White lacks the eyespace to settle right away and spends some time under attack. Consequently White does not have the luxury of collecting on Black’s move debt for the time being. Black uses this to get an extension out to the left side, which eliminates the need for Black to defend its weakness directly and sets up for a continued attack on the White group.

Move debt is also a concept that plays into jōseki analysis. Here is a standard outcome of the 4-4, low approach, one-space low pincer. A key part of understanding the professional evaluation jōseki is to understand that there is aji left in the marked White stone. Black can clean up this aji by subjugating the White stone by attaching on top at A, but this is slow. Black usually prefers to tenuki, incurring a move debt here.

The middlegame for this jōseki largely revolves around this unresolved move debt. White can get a good result simply by forcing Black to defend at A, for instance approaching from the side in sente. Black wants to avoid paying its debt directly by defending at A: it is much better for Black to capture the White stone inside a much larger moyo, because then Black gets to play the stone that would otherwise be at A somewhere more useful. The final evaluation of this jōseki comes down to which player is able to execute their plan regarding Black’s move debt.

Real-life example

In the final example, we examine how move debt translates into strategy in an actual game setting. Here we examine an amateur game between two SDK players; full disclosure, this is one of my own. Of course, this does mean that this example is not necessarily meant to showcase optimal play, though in this case Black actually does a decent job at it.

In the initial position, Black is at a serious disadvantage, having mishandled the jōseki in both the top left and right corners. White’s groups are very strong all around and there is not much to be gained by any reduction or invasion strategy: with this much strength, White is already guaranteed a significant chunk of territory and can simply ignore any invasions/reductions to focus on preventing Black from building in kind.

Understanding the uphill battle it faces, Black decides to play fast and greedy, taking the bottom side star point. Black’s strategy from this point on is to claim a very large portion of the bottom and left sides in as few moves as possible. Black accomplishes this by only establishing a skeleton of the territorial boundaries it wants, omitting multiple moves that would normally be required to secure it: thus Black takes on some serious move debt, in this case about five stones’ worth. In response, White can:

1. let Black’s greed go unpunished, in which case Black will have effectively gained the stones it owed but did not play; or

2. invade Black’s moyo, in which case Black can either:

   a. try to take profit in sente, close the score gap, and take the game to yose with a fighting chance; or

   b. fight inside Black’s moyo and force a do-or-die confrontation.

The goal here is to shake up the game-state. Playing normally at this stage will merely result in White solidifying its advantage and choking Black slowly into submission. Instead, by amassing several debts without paying them off immediately, Black threatens White with overly efficient play and forces White into a situation where it cannot close out the game without taking on a major risk of its own.

Black’s plan unfolds almost exactly as planned, albeit helped by a fairly significant White mishandling of the invasion of the bottom side. By forcing White’s invasion and building thickness along F8 through K8, Black manages to cheat White out of about two stones’ worth of debt that it would otherwise owe on the bottom side, all the while limiting White’s gains - enough to swing the game back in Black’s favor. From here Black has a sufficiently comfortable lead to take the game to yose. In the actual game, White recognizes the danger at this point and does what it can to resist, but eventually overplays its hand in its attempt to turn the game around: the final result was B+9.5.

Conclusion

The last example is just one particularly extreme example of how move debt emerges in actual gameplay and how one uses the concept in review. Move debt as a concept is universal, not limited to such egregious examples. Nor is it the only framework under which we can analyze this example: move debt is ultimately a lens through which we can examine the concept of strong and weak groups, and the two concepts are to some degree equivalent (though strength of groups is arguably more fundamental). The reason we frame certain conversations in terms of move debt rather than the more general idea of strong/weak groups is that strength/weakness of groups arises in many ways. Baduk is a complex game, and with complex subjects it is useful to have multiple essentially equivalent frameworks from which you can build an analysis. Strong/weak groups and move debt are just the beginning for us: in future articles we intend to continue to develop different ways to talk about what is ultimately the same concept at heart.

Furthermore, move debt is a convenient framework in which to organize the ideas of “fast” and “thin” versus “slow” and “thick.” Fast play is fast by virtue of omitting otherwise natural defenses, thereby incurring move debt and resulting in thin positions: play is slow when it includes the usual defenses and thus results in thick positions without much move debt. Hopefully this concept is useful for those of you who have heard experts refer to “fast” and “slow” play, but have a hard time understanding just what it entails and transitioning between fast and slow play yourself.

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