(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]
C[Ge's online school quality classes (with Weiqitv) week 2

Invading a variant of the Kobayashi opening

Zhang Yi Ming 3p

Translated by Daniel Hu 4d

Some proverb about fighting battles. Go is the same.
For common shapes, we need to get familiar with and know what to expect from them, so that in a real game, we can predict the future at a glance, and inform our decisions


Here is a game from Ge's online school
]
;B[pd]
(;W[dp]
;B[pq]
;W[dc]
;B[fq]
;W[cn]
;B[jp]
;W[pn]
;B[qo]
;W[pj]
;B[qn]
;W[qf]
;B[nc]
;W[ce]
;B[ic]C[so now the attention moves to the structure at the bottom. This is the subject of today's lesson - the invasions and most common ways of playing at the bottom]
(;W[dr]C[in the real game]
;B[er]
;W[dq]
;B[fo]C[B got this great shape. I must say W is not satisfied with this. So W needs to attack more severely])
(;W[hq]C[option 1

This is a very common invasion]
(;B[jq]C[this is a solid way to protect the right. Many players leave this position as white, and only come back much later.

I'll teach a good way to settle the position that is very easy to use

This is a sort of compromise move]
(;W[fp]C[attach]
;B[eq]
;W[dq]C[take the corner. This is very common in pro games]
;B[ep]
;W[eo]
;B[gp]
;W[fo]
;B[gq]
;W[go]
;B[hp]
;W[di]C[It looks like W's invasion stone has been eaten, but from the invasion, W sacrificed it, and exchanged it for this white wall and sente to build on it.

And B's efficiency at the bottom is low. Using tewari we can see it as ...

So this is a speedy and good way to settle the position]
;LB[eo:7][fo:3][go:9][ep:6][fp:1][gp:2][hp:10][dq:5][eq:4][gq:12][hq:11][jq:8]C[This would be a normal sequence, and B's exchange of 6 with 7 is bad. But most importantly black spent an extra move protecting at 8, making the shape inefficient.

Though W's exchange of 11 with 12 is bad])
(;W[ho]C[alternatively W can fight])
(;W[dq]C[or take the corner

either way the invasion at H3 has profited]))
(;B[hp]C[what if B decides to fight back?

There are now two moves.]
(;W[iq]C[if you don't have one of the ladders, you can only extend]
;B[ip]C[proper response

W has 2 moves]
(;W[jq]C[so normally you should play here]
(;B[kq]
;W[kr]
;B[lq]C[if B just retreats]
;W[gq]
;B[gp]
;W[eq]C[now this is much better for W]
(;B[fr]
;W[fp]C[now B's efficiency is much lower, even M2 is gote for B]
;B[er]
;W[dr]
;B[cq]
;W[dq]
;B[fo]
;W[ep]
;B[lr]C[this is gote and this is absolutely not good enough for B. Even if W responds, W has reduced B's area by much.]
(;W[jr])
(;W[gc]
;B[gr]
;W[hr]
;B[jr]
;W[hs]
;B[is]
;W[es]
;B[ks]
;W[fs]))
(;B[do]C[I'll show you an interesting move, B doesn't need to just accept W gets all the territory.

This is a tesuji.

W must be careful. This is a bit of a trick play

You must absolutely not just memorise joseki. You only learn a local position and not about the surroundings. Depending on different surroundings you need to learn to play differently.]
(;W[co]C[if W blocks]
;B[ep]C[now B can disconnect]
;W[fr]
(;B[dq]C[now there is a double atari]
;W[fp]
;B[cp])
(;B[fp]C[B does not connect!]))
(;W[cp]C[This is one response. Despite the compromise attitude, B can continue fighting]
;B[co]
;W[bo]
;B[bn]
(;W[bp]C[I played some kid at the school at they played here. Though this can protect the connection, B's intention has certainly been fulfilled]
;B[eo]C[this is sente threatening disconnection at F2]
;W[fp]
;B[fo]
;W[ep]
;B[cm]C[In this variation this is great for Black, getting such a huge wall])
(;W[bm]C[W must fight back]
;B[bp]
;W[an]
;B[ep]C[this is B's intention]
(;W[fr]C[W cannot connect]
;B[dq]
;W[fp]
;B[cq]C[W collapses])
(;W[eo]C[W needs to fight back - if B wants to disconnect so badly, I'll give it up to you, and accept your sacrifice]
;B[fp]
;W[lr]
;B[mr]
;W[fr]
;B[er]
;W[gs]C[W lives. This is one solution to B's trick play]
(;B[dq]
;W[dn]C[but W's profit is big])
(;B[dn]C[this is also possible]
;W[dm]
;B[en]
;W[em]
;B[fn]
(;W[cq]
;B[dq]
;W[cr])
(;W[dq]C[don't get captured]
;B[dr]
;W[cq]
;B[bq]
;W[cr]
;B[br])))))
(;W[fp]C[this is the other possibility. The idea of this is to treat C6 lightly, and focus on making sure B's outside is not too solid, and pierce through it if B fights]
;B[fo]
;W[ep]
;B[co]
;W[eo]
;B[dn]
;W[en]
;B[dm]
;W[cp]C[W obviously loses something by pressing B, but this is a good way to deal with the trick play. After W's invasion, W reduced B's territory significantly, and W's territory is very impressive.])))
(;B[gq]C[so B should play this move]
;W[lq]
;B[kp]
;W[mr]
;B[hr]
;W[is]
;B[cq]C[here is the standard follow up]
;W[dq]
;B[dr]
;W[cp]
;B[br]
;W[bq]
;B[cr]
;W[ck]C[so like this W has achieved the goal of invading and getting rid of B's territory.]))
(;W[gq]C[normally we consider W not very good here]
;B[gp]
;W[eq]
;B[fr]C[sacrifice]
;W[fp]
;B[er]C[first get some free stones in the corner]
;W[dr]
;B[cq]
;W[dq]
;B[fo]
;W[ep]
;B[jq]C[then get free stones over here]
;W[gr]
;B[ir]
;W[es]C[This does appear in pro games. But B's wall is perfect, and normally W isn't satisfied]))
(;W[ip]C[The saying for when to wedge is: first check the ladders on both sides. 

If they are both favourable, you should wedge.

In this case they both work for W, so B can't easily put W in trouble]
(;B[iq]C[which ladders?]
;W[io]TR[hp][jp]C[W needs to read if W can ladder either of the marked stones]
(;B[hr]C[B may not have the ladder, but that does not mean B cannot play like this]
;W[jq]
;B[gq]
(;W[ir]
(;B[hq]C[when W has the ladder, in no way connect here. Then in B's area, W has come in and beat up B.]
;W[kp])
(;B[kq]C[B can fight back here with ko]
;W[hq]
;B[cq]
;W[iq]C[W has no ko threats]
;B[dq]C[this is a territorial play for B. It looks like B's area has been totally destroyed, but all B's stones will still be useful later.]))
(;W[kp]C[this isn't very interesting for W]
;B[jr]
;W[jo]
;B[lq]))
(;B[jq]
;W[gp]
;B[hr]
;W[ho]
;B[gq]))
(;B[io]C[With appropriate surroundings, B can choose this.]
;W[iq]
(;B[jq]
;W[gp]
;B[ho]
;W[gq]
;B[jo]
;W[fp]C[this is totally fine for B. B's wall has no weakness and can go attack W

this is a common joseki]
;B[pl])
(;B[gp]C[absolutely don't play here]
;W[jq]
;B[kp]
;W[lq]C[now W lives and B's wall has two extra cutting points to worry about.

You can only play like this if W has to live very painfully, but not when W lives so comfortably as this.]))))))
(;W[dq]
;B[pq]
;W[dc]
;B[qk]C[from seeing B's games, teachers have found he often plays Chinese if his opponent plays 3-4 and Kobayashi if his opponent plays 4-4.

I recommend to viewers that they prepare a similar strategy before games that works well with your style. Especially in the short games these days, so you spend less time on the opening.]))