(;FF[4]
CA[UTF-8]
GM[1]
GN[mark5000's Guide to the Opening v2]
PC[https://online-go.com/review/358749]
PB[Black]
PW[White]
BR[9p]
WR[9p]
OT[Error: time control missing]
RE[?]
SZ[19]
KM[7.5]
RU[Chinese]
C[

-- chat --
trohde: Awesome, thank you!
]
(;B[pd]C[4-4, the star point (Japanese: "hoshi"). 4-4 is a flexible move that announces an influential focus while not favoring any one side. It is actually something of a modern invention and not a part of "classical" opening theory. Even so, it is now the most popular opening move, and its variations may be the most studied of all moves.

-- chat --
capahab: 1. From move 0: Q16 
]
(;W[dp]C[4-4, far corner. This move mirrors Black's flexibiliy and influential focus. Playing in the far corner prevents a cross game at the modest cost of allowing easier development for Black on the lower side.]
(;B[pq]LB[pe:1]LB[pf:2]LB[pg:3]LB[ph:4]LB[pi:5]LB[pj:6]LB[pk:7]LB[pl:8]LB[pm:9]LB[pn:10]LB[po:11]LB[pp:12]C[3-4, facing Black. This makes the right side wider (12 points wide) than the lower side and prepares for development on the right side. It also sets up an enclosure in the lower right corner, which projects influence towards white d4.]
(;W[dd]LB[dc:A]C[Dual 4-4. The most common choice is for White to remain flexible and see what Black will do. A is a common alternative that further mirrors Black's intention.]
(;B[nc]C[Enclosing here projects influence towards the wider right side and threatens to create an ideal structure for developing that area, once Black encloses the lower corner.]
(;W[qo]LB[po:A]C[So White often interrupts Black's development with some kind of approach. The high one at A is also possible.]
;B[np]
;W[qf]LB[fc:B]LB[re:A]LB[fq:C]C[White may continue by approaching the other corner either here or at A, both of which indirectly help the r5 stone while adhering to the modern style of speedy development around the corners, in which the most efficient territory is made. Black may continue by playing at the left two corners or by pressuring the outnumbered stones on the right side. Enclosing an own corner with B or C is also possible.

-- chat --
michaelpthompson: How marvelously informative! Not only the opening moves themselves, but an excellent and concise explanation of the reasons for them. Thank you so much.
]
)(;W[po]
;B[qo]
;W[qn]
;B[qp]
;W[pn]
;B[nq]LB[qi:B]LB[pj:C]LB[qj:A]C[This kind of joseki could also be played, with a follow up at A or B or C.]
))(;B[fc]
;W[cf]
;B[ql]LB[nc:A]C[Besides enclosing at A, Black can try for a speedier development by trading f17 for c14 and then creating a micro-Chinese framework on the right side.]
;W[qf]LB[nc:A]LB[qc:B]C[Approaching inside is most normal for attacking this micro-Chinese formation. Alternatives include A and B.]
;B[qe]
;W[pf]
;B[nd]
;W[pi]C[Kick and extend with r15 and o16 is a common way to pressure single stones. And White will help them with a tight extension high on the fourth line for escaping into the center if necessary.]
)(;B[pn]LB[ql:B]LB[qn:A]C[Another way to develop the right side is just to play there directly. The two-point high enclosure is the speediest one. Other moves are possible, such as a low enclosure at A, the previously shown micro-Chinese formation at B. White will in turn invade or approach the upper right corner, since Black did not play there beforehand.]
)(;B[fq]LB[cn:A]LB[pn:D]LB[qo:B]LB[jp:C]C[Similarly, this formerly common move has become less common, because the double approach at A is not as severe as previously thought, which means White is free to counter approach around B. If White does answer at A, which is fine, Black's follow up at C is now considered premature and instead should be either enclosing the corner around D or playing at the upper left corner.]
))(;W[cd]C[Facing 3-4 is possible for White but is disfavored because Black can develop in coordination with Black's other stones.]
;B[ed]
;W[ec]
;B[fc]
;W[dc]
;B[fd]
;W[cf]
;B[mc]C[If, for example, Black initiates a joseki at the 3-4 point such as this one, Black can finish by enclosing the corner facing the right side, which projects influence towards the right side, which is wider and ripe for development. This also helps the left three stones indirectly, helping to immunize them from immediate attack. White is hardly lost, but many players don't like to start off giving the opponent what they want like this.]
))(;B[pp]C[Dual 4-4 (Japanese: nirensei). This pattern was innovated in the 1970s by Japanese professional Takemiya Masaki as part of his "cosmic" style. Dual 4-4 signals an interest in influence, and is non-commital about the direction of play.]
;W[dd]LB[dc:A]C[White can respond in kind or one point off at A, same as before.]
(;B[fq]C[Black commonly approaches with a knight's move from the normal side, facing black's framework. It's a vanilla opening, but also one of the most powerful.]
(;W[cn]C[White commonly answers, though recent analysis suggests that it is not mandatory as once thought. White can play elsewhere and seize the initiative to be speedy. In that case, some kind of 3-3 invasion or approach against one of the star points would be good.]
;B[cc]LB[fc:A]LB[mq:B]C[Black has many options, such as invading here, approaching at A, or simply enclosing at B, which cedes the initiative to White but secures the corner and helps settle f3. For invasion continuations, see the variations below.]
)(;W[nc]
;B[cn]LB[qf:C]LB[dn:A]LB[fp:B]C[Suppose White doesn't answer the approach. Black often follows up with a double approach, which White should answer by attaching either to A or B. Mirror at C is another choice, provided the reader understands that mirror Go is not a sustainable strategy long-term.]
;W[dn]
;B[dm]
;W[en]
;B[cp]C[Attaching here has become popular.]
;W[cq]
;B[co]LB[fp:A]LB[dq:B]C[Now White can choose between A for center access and B for some territory.]
)(;W[hq]LB[cn:A]C[This low pincer is still a good alternative to answering at A in many positions. Black can approach at A, but the simplest way is to dive into the corner.]
;B[cq]
;W[dq]LB[dj:A]C[White must block this way, unless there is a stone around A.]
;B[cp]
;W[do]
;B[dr]
;W[er]
;B[cr]
;W[fr]LB[eq:A]C[White must stretch here.
A is a mistake.]
;B[cn]
))(;B[cq]C[As an alternative to approaching, Black can invade right away. Here I will discuss some common sequences that can be played whenever the 3-3 invasion is played.]
;W[cp]C[The direction you block may have some impact on what variations you try for, but generally it won't make a large difference which way you block.]
;B[dq]LB[ep:B]LB[eq:A]LB[fq:C]C[Three choices, from least to most common.]
(;W[eq]
;B[er]LB[fq:A]LB[fr:B]C[A for influence.
B for the corner.]
(;W[fq]TR[dd]C[White can only play this way if the marked stone is friendly, otherwise the influence won't be useful.]
;B[fr]
;W[gq]
;B[gr]
;W[hq]TR[dd]LB[dj:A]C[One problem with this simple variation is that Black has the initiative and can use it around A to nullify much of White's influence. The fact that the marked stone is friendly will help discourage this kind of thing right away, but Black is still happy to have stolen the corner.]
)(;W[fr]
;B[fq]
;W[ep]
;B[gr]
;W[dr]C[A trade occurs here.]
;B[fs]
;W[cr]C[White takes the corner in exchange for Black's good shape facing one side. White can manipulate this direction by choosing which way to block earlier.]
))(;W[ep]
;B[fr]LB[eq:A]C[This is a simple and good choice in many cases. White goes a bit soft on Black in exchange for the initiative. If Black instead answers at A it will translate to a variation shown below.]
)(;W[fq]LB[eq:A]LB[fr:B]C[Last is this jump.
A is normal.
B can result in fighting.]
(;B[eq]
;W[ep]
;B[fr]LB[bq:A]C[White can play elsewhere here or continue with A]
(;AB[gq]
;W[fp]
;B[bq]C[If White plays elsewhere, Black is expected to respond like this.]
)(;W[bq]
;B[br]
;W[gr]C[If White continues in the corner, White should wrap around both ends like this. It may look like a lot of cuts, but Black can only make good use of one of them, and White will reap good benefits no matter which is chosen.]
))(;B[fr]LB[eq:B]LB[gq:A]LB[gr:C]C[White can play elsewhere here, but generally you should not ignore attachments. White can try A or B for a simple outcome, but the ideal one is reached with C.]
)))(;B[pj]C[Three stars (Japanese: sanrensei). This is the original cosmic opening, but Takemiya moved away from it later in life in favor of dual 4-4s. Pros moved further away from it when pros revised their understanding of the value of corners to be more valuable. White's prescription is to approach or invade each side alternately, and then reinforce own corners. Rushing in to Black's formation too quickly is what Black wants.]
))(;B[qp]LB[ep:1]LB[fp:2]LB[gp:3]LB[hp:4]LB[ip:5]LB[jp:6]LB[kp:7]LB[lp:8]LB[mp:9]LB[np:10]LB[op:11]LB[pp:12]C[3-4, facing White. This makes the lower side wider (12 points wide) and therefore this will be the area for early development. It also prepares an enclosure in the lower right corner, which projects influence towards black q16.]
;W[dd]LB[dc:A]LB[cd:B]C[Again, White can choose here or A. B is also possible as a mirror opening. Just bear in mind that mirror Go is not a sustainable strategy long-term. The player who doesn't break the mirror loses.]
;B[np]LB[cn:E]LB[op:A]LB[fq:D]LB[nq:B]LB[oq:C]C[Black should enclose either here or A or B. The small enclosure at C is now considered slightly overconcentrated. Black can think about trading D for E before enclosing the corner, but White increasingly declines to answer such approaches in modern Go, and may counter approach Black's lower corner instead of answering D.]
;W[qc]LB[nc:A]LB[qf:B]LB[fq:C]C[Invading is perhaps White's most common answer nowadays. Variations for this invasion are shown elsewhere in the lesson. A and B are alternative ways to handle the corner, and defending one's own corner with C is also possible and calm.]
))(;W[dd]LB[pp:B]LB[qp:C]LB[pq:A]C[4-4, near corner. This move aims to match Black's influence. White's move here risks a cross game at the benefit of disallowing convenient development for Black on the lower side, for example, by playing move 4 at d3 facing white d16. As for Black, Black has the same move options as before with ABC.]
;B[dp]LB[cp:A]LB[dq:B]C[If Black does not want to play on the right side, Black can consider a cross opening, either here or at AB. This option is not generally available to Black if White opens in this corner. After the cross, White will seize the last corner and the players will follow the same principles as already mentioned, choosing the invasions, approaches, and enclosures, that seem appropriate to them.]
))(;B[qd]LB[nc:A]LB[nd:B]LB[od:C]C[3-4 (Japanese: komoku). This move has a territorial focus and prepares an enclosure at one of ABC to secure the corner. This was the most common opening move for hundreds of years and it is still very popular today because of its efficacy in securing the corner territory. The main feature of this move compared to 4-4 is that it is asymmetric. Thus, there is no etiquette for White to play on the left hand side. Rather, White can choose the corner that precludes Black from playing a certain opening of White's choice.]
(;W[dd]LB[dc:A]LB[cp:E]LB[dp:D]LB[pp:B]LB[dq:F]LB[pq:C]C[A White play in this corner, here or at A, means Black can't play any openings that involve the 3-4 facing Black's own stone. Black can follow up at B (which becomes an opening already discussed) or C (which is similar), or Black can choose a cross opening with one of DEF.]
;B[pq]
;W[dp]
;B[nd]LB[po:B]LB[qo:A]C[I'll take this opportunity to look at some josekis for White's approach of a 3-4 point, starting with A or B.]
(;W[qo]LB[pl:D]LB[np:A]LB[op:B]LB[qp:C]C[For the low approach, Black has five choices, from A-D to playing elsewhere.]
(;B[fc]
;W[op]
;B[oq]
;W[np]
;B[mq]C[If Black plays elsewhere, this is the situation Black can expect. White is happy to press Black down in sente (pronounced sent-ay, meaning it keeps initiative for White).]
)(;B[np]LB[ql:B]LB[op:A]C[Because of the former situation, the most conventional solution is to simply block the press down, either here or at A. This also pressures the white stone and makes it want a helper stone around B to be secure again. ]
)(;B[qp]
;W[po]
;B[nq]LB[qk:A]C[The kick at r4 serves the same purpose, preventing the press down. White is left with two stones that will be unsettled until White extends at A, which is quite big.]
)(;B[pl]C[Finally, a high pincer is a fighty choice for resisting the press down.]
;W[op]C[This is still a good move, but now it has consequences.]
;B[pp]
;W[po]
;B[oo]LB[pm:A]LB[oq:B]C[Black can cut and fight like this. The formerly common attachment at A has been shown to be a false tesuji (sharp move), which leaves Black in a better position. Instead, the drop down at B is preferred, and the players will continue the skirmish from there. ]
))(;W[po]LB[oq:A]LB[qq:B]C[For the high approach, Black's only good local answer is attaching underneath for territory. If Black plays elsewhere, White can attach to the Black stone at A or B.]
(;B[qo]LB[qn:A]LB[pp:B]C[White generally follows up with A. B is a special purpose move for building the lower side.]
(;W[qn]
;B[qp]
(;W[pn]C[Connecting is White's best move. If White doesn't fix the cut, Black in most cases should cut immediately.]
;B[nq]LB[qi:C]LB[pj:A]LB[qj:B]C[This is the joseki, with White finishing at one of ABC.]
)(;W[pm]LB[ql:A]LB[nq:B]C[If White connects loosely like this, it leaves a minor weakness at A, which threatens to connect under to the Black corner. With this weakness in mind, Black can play elsewhere without having to play at B, which is one of the ways in which AlphaGo helped innovate the opening theory.]
))(;W[pp]
;B[qp]
;W[oq]LB[pn:A]LB[qn:B]LB[qq:C]LB[pr:D]C[From here, many options are available to Black. C and D tend to be simpler than A and B. Regardless which you choose, the goal is to keep your stones stable and avoid getting surrounded on both ends.]
))(;B[pl]C[This pincer has disappeared almost entirely from professional play since AlphaGo. The reason is a new variation for White that claims too much corner for White.]
;W[mp]LB[oo:B]LB[nq:A]C[The variation starts with a large knight here. Black should respond at A, since we now know the cut at B brings a bad result.]
;B[oo]
;W[on]
;B[no]
;W[pp]
;B[nq]C[This joseki will look familiar to Go veterans. Black tries to keep White split, but notice how many corner points are at stake and you can start to see why the pincer is no longer played much.]
;W[op]C[Push in here.]
;B[np]
;W[oq]TR[qo]TR[ro]TR[so]TR[qp]TR[rp]TR[sp]TR[pq]TR[qq]TR[rq]TR[sq]TR[pr]TR[qr]TR[rr]TR[sr]TR[ps]TR[qs]TR[rs]TR[ss]C[The corner skirmish is not over, but you can already see what White has claimed. This is considered too much to be a fair result to Black, so the pincer isn't played as much nowadays.]
)(;B[qm]C[Similarly this tight pincer fell out of fashion.]
;W[qq]C[White should attach here to start, which gives you some idea why pincers got less popular. We know the corner territory is valuable, so why let your opponent claim some of it when there's a pattern that guarantees it for you (attaching underneath)?]
;B[mq]C[This was the most common answer.]
;W[pp]
;B[pr]LB[oq:A]C[And then Black descended here, even though AI suggests that simple A is better.]
;W[np]C[The joseki that continue from here are deemed good for White.]
)))(;W[pp]LB[dc:B]LB[cd:C]LB[dd:A]LB[cp:E]LB[dp:D]LB[dq:F]C[A White play in this corner means Black can't play any openings that involve the 3-4 facing White's stone. Black can follow up at A or B (both of which become openings already discussed) or C, or Black can choose a cross opening with one of DEF.]
;B[cd]LB[cp:B]LB[dp:A]C[White can choose A or B, as usual.]
;W[dp]C[In this opening, Black typically encloses the upper right corner in the usual spots, and White will approach the upper left corner.]
)(;W[dp]LB[dd:A]LB[pp:B]C[Finally, White can prevent a cross opening at the cost of letting Black choose whether the 3-4 stone faces a friendly stone (A) or a hostile stone (B).]
))(;B[qc]LB[nc:B]LB[nd:A]LB[pd:C]C[3-3 (Japanese: san san). With this move, we get into less common opening moves considered less efficient than 4-4 or 3-4 points for one reason or another. That doesn't mean they can't be played, however, and either player can play one of these other points whenever a 4-4 or 3-4 point is suggested in this lesson. Back to the 3-3 point: this move is more territorial than 4-4 and 3-4. It grips the corner in one move but does not claim much territory (only 4 points solid cash). Because little corner territory is at stake following this move, the corner with a 3-3 played instantly becomes an uninteresting area. Your attention should go to other corners. When you do get to this corner, common approaches are AB or C.]
)(;B[qe]LB[pc:A]LB[qc:C]LB[od:B]C[3-5 (Japanese: mokuhazushi). This is an aggressive move that aims to get the press down with B following White A. White can prevent this by approaching at B, but then Black gets the corner. While neither option is bad per se, White can avoid it by invading deeper at C or just not playing at the corner at all, which would force Black to enclose at A, which is slightly overconcentrated.]
)(;B[pe]LB[oc:A]LB[pc:B]LB[qc:C]C[4-5 (Japanese: takamoku). This move is similar to 3-5 in that it invites White to take the corner with one of ABC, giving Black the chance to pressure it from outside. White ignoring it would mean Black encloses the corner, most likely at B.]
))