# Why don't we open at tengen

Keywords: Strategy

From what I understand of the literature. The Pro's don't open with Tengen, because there is essentially too much flexibility in the openings, and it makes it difficult to work out lines of play around tengen as a focus. The variations on the Joseki would just be too many so there are no Joseki, though the great wall strategy is fairly well understood and practical.

Amateurs, from 25 kyu to 7 dan, open in the corners at komoku, hoshi, sometimes takamoku or sansan, or, when they are really in an adventurous mood, at mokuhazushi [1]. Why so? Well, of course we all know the theory: corners, then sides, then center. But probably we are merely imitating the pros. Bruce Wilcox, AGA 5-Dan and author of quite a few original ideas, has shown us the virtues of the Great Wall, opening at tengen.

• Suppose there is one "best point" on the board - then this point must be tengen.
• Fhayashi: Why? It's the only point with no symmetric counterparts, but that doesn't make it the best point.
• KarlKnechtel: Because of the symmetry and the supposition that there is one "best point". If the best point were not tengen, there would be either three or seven equivalent points, contradicting the uniqueness.
• Fhayashi: but perhaps tengen is the one "worst point"? Or the fifth worst point (after the four corners)? Or the seventeenth (after each of the four 1-1, 1-2, and 2-2 points)? I think I see your point now, but the above statement is circular.
• RafaelCaetano: It is a true statement, but it's trivial (I'd say "silly"). It doesn't depend on any "real" go knowledge, only on the symmetry of the board. In that kind of situation, "unique" is interesting only if it means "unique up to symmetry". It's not "circular" but yes, you can also say that if there is one worst point, it's tengen.
• Kirk: My argument that tengen is a key point (I wouldn't call it the "best point"), hinges on the idea that Go is not a forced draw (certainly arguable). If Black does not play tengen (ever), then White could play MirrorGo and achieve a draw (don't ask me to prove this rigorously). Since Go is not a forced draw, Black must play tengen at some point. However, there is no reason to believe that tengen needs to be Black's first move. It could be that there is a whole set of (symmetrical) games with a forced win for Black. To me, the key question to ask is, when is playing tengen worth giving up sente?
• Hu: For very small sizes of Go boards that have been exhaustively analyzed (up to and including 6x6), tengen is the winning move. The case for tengen in 9x9 is also very strong. By induction, tengen is suggested on 19x19.
• Fhayashi: I have to disagree, as the utility of the tengen in smaller boards may reflect the fact that they are influence-oriented corner moves on multiple corners simultaneously - i.e. tengen in 9x9 is a 5-5 play on four corners at once. 5-5 may not be good as 4-4, but 4 X 5-5 is better than one 4-4.
• Rakshasa: By the same logic, if you give your opponent handicap at each of the 1-1 points, then he will be able to play against you as if he had 4 normal handicap stones. Since it is symmetric, it must be good, right? IMO, the best move does not need to be in a symmetric position. If the best move is on komoku, it doesn't matter which komoku you choose. Though it will propably force white to play in a specific location. (As opposed to tengen, which gives white 4 or 8 possible places that are the best moves)
• Fhayashi: Not sure of what you mean, Rakshasa. I'm just arguing that the 'goodness' of tengen in a 9x9 board does not necessarily translate to 'goodness' in a 19x19 board. My overall argument is that tengen is not necessarily a good play, let alone the best play, in 19x19 go.
• Rakshasa: Perhaps you missed my point because it was a reply to Hu, not you. ;)
• Professionals have opened at tengen during the exciting times of the New Fuseki creation.
• Professionals are always battling for control of the center (a former professional has told me so in a game comment).

So, why don't we open at tengen more often? Have you ever opened at tengen? What are your experiences?

[1] See named points.

HolIgor: First of all there is Yamashita Keigo who does open at tengen nowadays. Look at Van Rongen's page. Yamashita Keigo is his new hero. [See also Yamabe-Hashimoto tengen game.]

Calvin: He hasn't done that since about 2002. Now that he's a 9d and erstwhile major title holder, he is playing more conservatively.

Second, I do play tengen with White quite often against one-sided fuseki (BQM 386). Not as the first move but quite early in the fuseki. I win more than lose but that is 4k* level. Nobody else wants to try.

It is a better policy to start in a corner, as it is more difficult to gain territory early in the center. -- Tim Brent

HolIgor: While your statement is correct, playing first move at tengen sets up a ladder breaker for all four corners. It is a great advantage in the forthcoming fight.

And I would recommend you to look at the value of the corner plays a little bit differently. A play in the corner is good not because it helps to gain territory but because the corner is the place where building up a live group takes the least number of stones. In a way the moves in the corner are thick, provide the safe base from which to develop further strategy. A stable group in the corner does not always develop into a territory, but its stability may be helpful in obtaining territory elsewhere.

Jan: If I'm playing 9x9 I always want to start at tengen and always I'm afraid to, so I play in the corner instead :-(

HolIgor: Maybe you'd have a little bit more courage if you knew that professionals start 9x9 at tengen. With 9x9 this move is evidently very strong.

Fhayashi: For 9x9, the tengen is more like a quadruple 5-5 point. Like playing an influence-oriented opening in four corners simultaneously.

Jan: OK, I'll start to try it! But I usually don't need ladder breakers on 19x19 because my joseki knowledge is awful :-)

Kirk: I absolutely always play tengen on 9x9. I invariably lose if I don't. Strangely, the converse is not the case.

TakeNGive (9k): I've opened at tengen a few times (maybe 5% of the time?), with mixed results. Sometimes it seems effective for White in 2- and 4-stone handicap games. I recently lost a game as Black, where White opened with 10-10 (tengen) followed by three of the 10-3 points while I took the corners; but subsequent analysis showed a reading blunder late in the game. I've seen a very strong amateur player get good results opening at tengen. A Japanese pro (Kubomatsu) opened at tengen in all his games in the 1934 Oteai, after which he concluded that opening at tengen is feasible but difficult (see John Fairbairn's Mindzine article).

Dave Sigaty: Pieter Mioch touches on tengen in his Daigo series episode one. I think that he makes a nice point about the purpose of a play at tengen which I reproduce below.

"One thing you should realize when talking about tengen is that this play is not about trying to make territory in the middle of the board. This can easily be seen below:"

Wasted Move

11

"You won't see this kind of shape in your own games very often. But, now that you have it in front of you, it is obvious that a black play on the (marked) spot would be a wasted move. It is not necessary to defend this territory. If you really want to do something in the middle, a move at the 14-9 point looks better."

No, you probably won't see this kind of shape in your own games. The tengen can be used to help keep White out of your center territory, like below. Black doesn't have to take all of the territory around the tengen point to profit from it. Apologies in advance for the poor picture.

11

"This is not to say that Black cannot put his tengen stone to good use when making a large territorial framework, a moyo. Takemiya's games of the 1980s are a very good example of how to make huge side/center oriented territory. I still, however, would like you to only think about the possible territory one can make with a tengen stone as an afterthought and not a prime directive. "

Dave: Basically I think that compared to a move in the corner or the side, the value of a play at tengen will have to be justified by its relationship to other stones played. Playing tengen on the first move means giving the opponent sente to choose a strategy that tries to prevent you from setting up such optimal relationships.

Dieter: Sure. And given the fact that pros rarely play at tengen, I assume they know how to "punish" tengen. But we amateurs are not able to find such a strategy. I wouldn't even know what such a strategy looks like. So I intend to find out for myself and I encourage others to do the same.

Bill Spight: Conversely, you might say that few players, even pros, know how to utilize an opening tengen play. ;-) When the New Fuseki was in vogue, of course a lot of games began with tengen. By 1970, statistics with pro komi games showed Black winning only 1/3 of the time with initial tengen, I was told.

Kris Rhodes: Someone above said something to the effect that playing Tengen gives the other player sente and hence allows them to set things up so you won't be able to use that Tengen play in the future of the game.

It occurs to me that an interesting way to set the game's agenda even after playing Tengen as Black would be to not take any of the corners but instead to reply immediately to White's opening corner plays in the corners White plays. White's still in Sente, of course, but by placing all the kakari where you want them to be, you've kind of set the future course of the game to an extent, which is kind of like a meta-sente, sort of.

I'm only 15 kyu so ignore what I just said.

Illich: I have put winning percentages of tengen as first move here: Tengen Statistics

Kungfu philosophizes here:

Depends how you think. You could think tengen is a wasted move if you want to enclose the center, but then it takes a lot more moves than just one, to accomplish that. But with just one move you can have a radiating star in the center of the board which can act as a nexus for all your groups. "Don't get surrounded" (shut in), well, don't. Then you just need to worry about territorial balance. Just think until you see how your moves affect territory and how your opponent can respond with regard to territory. A tengen stone could be like the eruption of a volcano straight into the air, connecting or covering everything. Do you really want to spend 10 or 15 moves enclosing the center (and your opponent probably will not let you get that much) or could you rather just occupy the pass with your most powerful soldier: the first move?

Something else. If you are playing a (basically) evenly ranked game, then taking the first move at tengen as Black, you are allowing yourself to play White but with some power in the center. This could be the edge which pushes the game in your favour. If you are just playing "conventional" Go and ignoring tengen in any of your moves, then that decreases your winning percentage when moving on the tengen first.

• Remember that playing with this idea you are also paying double the komi in exchange for tengen. You were enjoying komi as Black and now you are giving it as pseudo-White. -- Dave Sigaty

White moving on the tengen first is probably bad though, because Black will get too many corners and depress White's center.

Anyways... a final comment. What's the real difference between an 8- and 9-stone handicap game? Or a 6- vs a 7- vs an 8- stone handicap game? Are the handicap stones placed in a truly progressing way, or should they go around the edges before the center? Or should they always have a center stone? There's a proverb that Corner is gold, side is silver, center is grass, why is that proverb there?

Phlegmatic: Speaking as an 18k KGS player, I find that many of my games hinge on the issue of who plays at (or near to) tengen during the early mid-game.

At my level, it seems to make a big difference, and although I've not checked the stats, I feel like I usually lose if I don't play there first. In my humble opinion Tengen is often a huge play psychologically, provided it is timed right.

So, in an even game, I'd be loathe to open at tengen as White, as Black now has an opportunity to fill two corners, but psychologically I'd feel very comfortable about opening at tengen as Black, despite komi. Feeling good about the middle right from the start definitely boosts my confidence and I'd like to think that improves my play.

Charles Matthews: If you go more deeply into central strategies, they are clearly difficult.

Something that came up unexpectedly as I was doing database searches to track down 'one-percent patterns', i.e. patterns common enough to come up in 1% of pro games.

Action at a distance

When Black starts at the 4-4 point, the next play in the 11-11 square based in that corner is sometimes the marked one: which is most likely outside influence or some other consequence of a fight in the lower right. Not true in the same way for other corner plays, I believe. So it does seem that top players can take the whole diagonal length of the board in their stride, and play deliberately to co-ordinate across the middle.

I think this is only just in range of the perception of good amateur players.

I think there could be another reason for this. A stone at the 4-4 point asks less for a local continuation than one on other points. Therefore, it might be that some extensive fighting takes place on the lower or right side or the lower right corner when the stone is on 4-4, while with a stone at 3-4 the pros would have come back to this corner before starting the fight elsewhere. -- Andre Engels
Yes, that kind of reason too. I've checked some figures and it seems to be 1.5% of the time for the 4-4 point, 0.5% for the 3-4 point, that the otherwise empty 11x11 space is next occupied as shown. Charles

Jasonred: I am a great fan of Tengen. It is all part of my idea that tengen is the "perfect" place to play, and the opening move of Kami no Itte. As such, I have come up with a (even more?) (crackpot?) theory and hypothesis about Tengen, Center, Corners.

Vesa Laatikainen: I started my tengen years in June 2001, in the last round of World Amateur Go Championship. I had a week before bought Yamashita's book (English: Challenging Tengen, Japanese: Tengen e no Chousen; Nihon Ki-in; 700 yen) and decided it is time to start something different.

The first trial ended in failure, but after that I've applied tengen in Finnish top tournaments, Nordic championship tournaments and European Ing Memorial tournament, with relatively good results. It should be noted that with played in tengen I have 100% win ratio (circa 10 games).

I've planned to write an essay (in Finnish) "My Tengen Years" ("Kun pelasin tengenin") about this phase, but probably only for the small Finnish Go community to be safe from critics....

Playing tengen is fun. I remember in the Nordic Championship when I customarily played tengen and looked around the other players pondering the boring, old, set course of openings. (Please, don't be offended, it was the curious feeling of that moment.)

Bob McGuigan: I don't begin with tengen because it is too difficult to make it effective against good play. I guess I agree with Bill in this regard. Obviously it is a possible move, but I'd venture to say that people win with it more because their opponent got confused (even pros) than because of the inherent virtue of the move. However, it is challenging for both players. The tengen player has to make the move useful, his opponent has to make it less useful. Vesa seems to have played it to break the routine. It can be very effective against a player who knows the standard shapes but doesn't really understand go fundamentals.

Charles Matthews: Yes, I've been interested for a while in the parallelism between this view of early central influence, and the effect a big ko fight can have in 'unbalancing' and 'de-familiarising' the game: bringing 'fighting fundamentals' to the fore.

Kirk: Perhaps tengen is the best opening move, but we humans are just not capable of conceptualizing the correct follow-up. Bob said that it is "too difficult to make it effective". Perhaps this is a statement about our limited human capacity rather than a fact about the mathematical probabilities of making it effective.

Vesa: Did I say that I test run the tengen in our club meetings and in my mail-go games before trying it in important tournament games? Background study never hurts.

Yes, a part of the tengen is to get your opponent to overreact and the other part is to inspire your own game. And the background study enables you (the tengen guy) to have a plan while the opponent just tries to find something useful.

-- Vesa

Reinhardt: Here is a link to John Fairbairn's article on Tengen. There is a part discussing that a possible reason pros seldom use the Tengen opening is that it is statistically more difficult to analyze variations and win percentages of these variations. In other words, it is not necessarily a bad opening move, just more difficult to handle. In fact it might be the best opening move, but that would be very hard to justify.

tsjanl: The Go club in Amersfoort, the Netherlands, organizes a yearly tournament (in 2003 on August 10), in which the first stone has to be played at tengen and strength difference is expressed in komi. The reason behind it is that Amersfoort is in the centre of the country.

mAsterdam: Strictly topographically, Amersfoort is in the centre of the country. Economically Rotterdam may start at Tengen, Politically Den Haag has reasons to do so.

Tomas, 10k: I'm suprised not to read anything about the history of Tengen-opening. Some centuries ago, people used to consider it very rude to open at Tengen becasue they believed it would lead to certain win. Traces of this can still be found in Japan where it is quite common to "ask" your opponent if you may start at Tengen before doing so. I always thought it was this ancient believe that made Tengen-opening so uncommon.

John F.: You will find plenty at http://www.msoworld.com/mindzine/news/orient/go/history/kubomatsu.html. As regards the etiquette point, I don't believe it. Have you a reference? I suspect you may be confused by a famous story in which Kuroda Shuntetsu apologised to Murase Shuho before playing tengen in desperation after a dispiriting series of losses with Black. (1879, I think, but I'm quoting from memory).

Anonymous: Mok Chin-seok's 5 tengen-opening games (all wins as Black - see tengen statistics) are all from 2001 KBS Cup, which is a quickplay tournament. (Is this opening a good strategy for a blitz game?)

Andre Engels: Perhaps more generally using an unusual opening is a good strategy for a blitz game. Your opponent has less possibility to think it over at the spot, so the 'prepared vs unprepared' advantage is larger than in a normal game.

Interestingly, the first four games show exactly the same -- sequence. In 5th game, was played at (3,5) instead of (4,4), and the opening moves were rather different.

Tengen opening sequence in 2001 KBS Cup.

a was played instead of in the 4th game. b was played instead of in the 1st game. c was played instead of in the 4th game.

grimani: By the same argument of symmetry, should there be any one *worst* spot, Tengen would have to be it as well. Or any other adjective you can think of.

I prefer my Tengen being, by far, the sexiest.

There's an IGS player around 6 kyu (not me) who has had some good success with this kind of opening strategy as Black:

Tengen strategy

Black starts with tengen and then takes two adjacent hoshi. The problem with starting with tengen as I see it is that White can then play in such a matter as to make tengen seem misplaced in subsequent middle-game fighting. White also has the option to play quietly and make Black prove that tengen makes up for giving away the komi with the first stone. White also has the option to play to transpose to, for example, the all-stars opening. I think the main success of the tengen opening is when White considers it insulting and then loses mental balance, or when White considers it an overplay and then really does make overplays in an effort to "punish" it. -- Andy Pierce

mdh: So what is White's best stratagy against this triangle based opening.

Calvin: I've heard a few pros say that white can play at a next or very soon, to prevent black from playing at b and making miai of c and d. Black doesn't have a severe attack, and his moyo would be disrupted. What black wants is for white to make some kind of inside approach at e, for example, and then black can pincer and start making useful.

Jesse: On a somewhat related note, I read something interesting in this Pieter Mioch article on gobase.org. Apparently Go Seigen has said that the best known sanrensei is actually the worst possible one (too concentrated on one side of the board), and that the one you have shown is second best. The next diagram shows the best sanrensei, according to Go.

Best sanrensei?

Deternal: Couldn't this last board be used for an alternate Great Wall strategy as well?

Jais Bane: Tengen has interested me as an opening ever since I first started Go, and I find that my thoughts lead towards it whenever I think about strategy. I like to play an influence oriented game, and I greatly enjoy fighting, and so the potential that Tengen has for this makes me try to develop strategies for how to use Tengen as an opening.

I have heard "When playing Tengen, if it is used, you win. If it is not, you lose." This refers to the the thought that when you open on Tengen you lose sente and you double the komi, meaning Black plays like White without komi and White plays like Black started with two stones. Yet this is Tengen viewed from a traditional, territory oriented strategy. Modern Go also lets one play with an influence based strategy. Tengen has influence over the whole board because it doesn't claim any territory, and from Tengen one can press the opponent flat, keeping them from making large territory. Or, one can split the connections apart, forcing a large battle because neither side can make any territory.

When you open at Tengen, you must play every move so that it has a relationship to Tengen, otherwise it's influence means nothing. Corner approaches should be light, and high, which will give you a strong connection to Tengen.

Balance and position are very important. Even though your moves are connected to Tengen, they should not be clustered around the center. It is important that you draw power from Tengen, but you should play to weaken your opponent, not to strengthen your center position.

The diagram below illustrates powerful approaches you can use against traditional/territory oriented openings.

Approaches to use when opening at Tengen

A two-space high approach is a strong response to komoku and mokuhazushi, allowing you to develop lightly and to keep corner territory flat and heavy.

A large knight's approach to mokuhazushi, illustrated at a, is also strong and is good for balance, but it is more likely to lead to heavy fighting.

A large knight's approach at 4-7 is strong and claims the side and is good to disconnect a corner.

The knight's approach at 3-5, illustrated at b, threatens to steal the corner from White, but it can be separated from tengen easily.

The one-space high approach at 4-6, illustrated at c, is a strong approach and leads to heavy fighting.

Both b and c are important for balance because the large knight's approach can be too close to tengen if several high approaches are used.

Sansan (3-3) is perhaps the worst opening to use in response to Tengen because the shoulder hit at hoshi is very strong and makes White very flat.

The openings below are strong responses to opening at Tengen because they threaten its influence and try to isolate it.

Openings to use in response to Tengen

However, when these openings are used by Black, Tengen is a strong response for White and can force Black to abandon the influence strategy.

The 5-5 point is a strong response to Tengen. The strongest approaches are at hoshi and sansan, but both of these are not connected to Tengen, and so should not be played. Black's best response is to tenuki.

Ootakamoku and Oomokuhazushi are light openings, but they heavily favor a side and when a low knight's approach is made they can become unbalanced in relation to the rest of the board.

Hoshi is a very variable opening is good for balance and black will normally tenuki. However, Black can approach in many ways and can unbalance White's position.

The game below is how I would respond to an opening on Tengen.

White's Strong Counter 1-5

The parallel 5-5 opening forces Black into a weak san-ren-sei which makes ineffective use of Tengen.

White's Strong Counter 6-10

White attacks the center and the pinwheel is played out to give both players an opening to attack the other.

White's Strong Counter 11-15

Black plays to attack White's deepest group, White plays to make a base, and Black plays to strengthen his group.

Alternatively Black can tenuki, approach White's corners, or attack White in the center, but doing so leaves his group weak, and an effective White attack can negate his initial play at Tengen.

White can defend with a, or invade at b and c, with the heaviest fighting resulting from c.

I've put a lot of thought into opening at Tengen, and critiques of my thoughts are appreciated.

I plan to continue opening at Tengen, to develop more and stronger strategies, and I would like to see Tengen become a strong and common opening like hoshi.

Jion: For what my two cents are worth, I would like to play at tengen every now and then, simply because one is forced to learn how to use all of one's stones more effectively. It also forces one to think of the game from a whole board perspective more and to truly create a strategy, rather than relying on corner joseki and fuseki. I think it is great as a learning game, but I personally wouldn't expect to win, since I don't feel I have a good enough intuition of the whole board yet to make it interesting for myself.

starline: Is it considered rude to play at tengen? If it was in the past, is it still now? In his book 'The Game of Go, the National Game of Japan' (first published in 1908), Arthur Smith says that it used to be considered "exceedingly impolite and insulting" to play the first move at tengen. One reason he gave was: "It has been explained to me that the reason for this rule is that such a move was supposed to assure victory to the first player, and it is related that when on occasion Murase Shuho had defeated a rival many times in succession, the latter, becoming desperate, apologized for his rudeness and placed his stone on this spot, and Murase, nevertheless, succeeded in winning the game, which was regarded as evidence of his great skill." The other reason was: "It has, however, been shown by Honinbo Dosaku that this move gives the first player no decisive advantage, and I have been also told by some Japanese that the reason that this move is regarded as impolite is because it is a wasted move, and implies a disrespect for the adversary's skill, and from what experience I have had in the game I think the latter explanation is more plausible. At all events, such a move is most unusual and can only be utilized by a player of the highest skill."

Tamsin: I don't believe it is considered impolite anymore. Yamashita Keigo, former Kisei and very popular young player, has used this opening many times. Also, thinking about the opening has changed a lot since the days of Arthur Smith (he was writing prior to the New Fuseki revolution of the 1930s, and so the range of possibilities is a lot wider than it used to be. Still, obviously bad moves such as playing a first move on the second line would surely be regarded as rude, and there was an occasion a few years ago when a young Chinese player, I forget who, angered O Meien by playing at the 6-3 point instead of taking a corner. So, I suppose the moral is, tengen and other second-choice opening moves (the first-choice ones being 4-4, 3-4, 3-3 and 5-4) are nowadays fine, but maybe you should be careful about playing very experimental moves except when you know your opponent well and can be sure they won't feel offended.

As a footnote to this, it seems a little ironic that O should have been so annoyed, because he himself is noted for his strange and inventive openings! Meienism

Unique opening

ilan: I believe that this game features a unique opening pattern http://files.gokgs.com/games/2004/2/20/tetra-ilanpi.sgf The sequence was motivated by the game negociation in which one side insisted on giving a handicap while the other insisted on an even game. Interestingly, Black's first move ends up being very useful winning an extra 3 points while White's first move ends up being totally useless and even loses 1 point.

binky? I’d like to question a few statements made on SL about my favourite first move, both as Black and as White.

I note a very recent change in attitude to tengen openings on this page.

I’m pleased to see the new page, WhyWeDoOpenOnTengen.

Duhii: I open at tengen always as black. The reason for this is that I'm a pathological fighter who loves joseki like the Taisha joseki and the Large avalanche, making a play at tengen very useful in the upcoming fighting. This is at the high kyu to low dan level in KGS. These games usually end in the death of a dragon. White's answer to tengen should be to attach and crosscut in the center, resulting in a pinwheel shape. Playing tengen games after tengen games, I feel this is how it's supposed to be answered - of course giving very unobjective value for the active central position white gains this way, compared to making more traditional claims in the corner. Double 5-5 points sounds like an intriguing counter, but I have sadly never had the chance to play against a white player using this strategy.

The center point must be the strongest move on 19x19. Looking at the analysis of smaller boards, the smaller the board the easier this recognition about the central point becomes. 10-10 point is just so far from the corners that their relations in influence become mind-boggling. We can't even begin to explain how the 6-6 or 7-7 points work towards the corner, so we don't have any chance at giving any explanation about the 10-10 point. In this dead-end debate about the good and bad points of tengen, which pro has ever claimed it was a bad first move? Difficult, yes, and complicated too, but definitely not bad.

Anonymous: AI like AlphaZero, LeelaZero, ELF, and KataGo do not rate tengen very highly, and would very much prefer playing towards the corner. Hence why we don't open at tengen.

Patrick Traill 2020-10-28: My KataGo (1.6.1 with g170e-b20c256x2-s5303129600-d1228401921) thinks the score with an empty board should be 0.7 for White (after about 7,000 playouts), but if Black plays tengen it becomes 1.7 for White (~6,000 playouts). But even if that meant we knew it was sub-optimal, it need not dissuade us from playing it, if we think our opponent will do worse against it.

• fool 2023-03-03: Really, 0.7 for White? I guess that mean 0.7 after komi. (Which is how much in this case?)

fool 2023-03-03: Actually, I wonder: How much komi would people here bid for black if black had to open tengen? (See AuctionKomi. So something like this: Put a black stone on tengen. Then you choose how much komi. Then your opponent chooses black or white. What komi do you choose?)

### Myths and Half-truths

• "if there is one worst point, it's tengen"
• "It is a better policy to start in a corner, as it is more difficult to gain territory early in the center"
• "Playing tengen on the first move means giving the opponent sente to choose a strategy that tries to prevent you from setting up such optimal relationships."
• "White moving on the tengen first is probably bad though, because Black will get too many corners and depress White's center."
• "Perhaps tengen is the best opening move, but we humans are just not capable of conceptualizing the correct follow-up."
• "Corner approaches should be light, and high, which will give you a strong connection to Tengen."
• "3-3 point, is too early since it gives Black the 4-4 point which coordinates with tengen."
• "There is no territory in the centre"
• "It can be very effective against a player who knows the standard shapes but doesn't really understand go fundamentals."

• "There is no territory in the centre"
• "...this play is not about trying to make territory in the middle of the board."
• "Statistically, ... there is no reason to believe opening on tengen is inferior to corner play."
• "...with played in tengen I have 100% win ratio (circa 10 games)."
• "Professionals have opened at tengen during the exciting times of the New Fuseki creation."
• "Professionals are always battling for control of the center"
• "few players, even pros, know how to utilize an opening tengen play."
• "...one is forced to learn how to use all of one's stones more effectively."