This is a joseki that arises after black plays the 4-5 point and white plays the 3-4 point. Published in Go Journal last year.
(;AB[po]AW[pq]AB[np]AW[qo]AB[pp]AW[qp]C[What is black's next play?]AP[goproblems]
(;B[qq]C[Please check - there is another option];W[qr]
(;B[rq];W[rr]
(;B[oq];W[pr]
(;B[qn];W[rp]
(;B[ro];W[sq]
(;B[pm]C[Gives white a small corner and sente but black's thickness is formidable. Good jobRIGHT])
(;B[rm]C[White capturing that stone is small potatoes. Play somewhere else.])
(;B[or]C[Not yet: you have a cutting point to take care of.])
(;B[pn]C[You have the right idea, but there's a better way to connect.]))
(;B[or];W[rn]C[You could do better.]))
(;B[rp];W[ro]C[Congratulations, you just threw away three stones.])
(;B[or];W[qn]C[White escapes being enclosed, and black wastes the aji of his two stones.]))
(;B[pr];W[oq]C[Q2 will be lost.])
(;B[qn];W[rp]C[Black can now not get both marked moves in sente.]MA[oq]MA[ro])
(;B[ro];W[qn]))
(;B[pr];W[oq]C[Not good for Black])
(;B[oq];W[rq]C[Black does not make full use of his aji.])
(;B[qn];W[rq]C[Black is not using his possibilities well enough.]))
(;B[oq]C[Please check - there is another option]
(;W[pr]
(;B[pn];W[or]
(;B[nr];W[rm]C[RIGHT])
(;B[mq]C[Good - black does not go for the maximum at the edge, but gains in thickness.RIGHT])
(;B[qn];W[mq]C[Inconsequent]))
(;B[qq]
(;W[rq];B[or];W[qr]
(;B[pm]C[RIGHT])
(;B[qn]C[The cut at Q6 is very painful aji.]))
(;W[qr]C[This variation is not played by the computer in the problem, not because it is wrong (it is not), but because the variations after this are not as clear-cut.];B[qn];W[rp]C[From here on, this is just one variation of various.];B[ro];W[rq];B[pm]C[RIGHT]))
(;B[qn];W[pn]C[Results in an unnecessary and often not so profitable fight.]))
(;W[qq];B[pn];W[qm];B[ol]C[Only the most common of various variations here.RIGHT]))
(;B[qn];W[pn]C[Now black is in trouble.])
(;B[pr]C[];W[oq]C[The cut at R3 does not work, so Q2 gets lost.])
(;B[pn]C[];W[oq]C[Too soft on white.]))