This position occurred in a game between Sakata and Hashimoto Utaro. Threats to connect out to the black stones on the left are significant, although they are not realised in he variations given.
(;GM[1]FF[4]CA[UTF-8]AP[CGoban:2]ST[2]
RU[Japanese]SZ[19]KM[0.00]TM[]
PW[White]PB[Black]AW[na][ra][lb][ob][pb][qb][mc][nc][pc][ld][le][mf][nf][pf][nh][ni][pi][qi][nj][qj][ll][ql][lm]AB[kb][rb][kc][oc][qc][rc][kd][od][pd][qd][ke][me][lf][kg][lg][mg][li][mi][mj][pj][kk][lk][nk][kl][pl][km]TR[pf]C[White has just played the triangled stone what can black salvage from his group in the top right?]
(;B[rf]CR[rf]
;W[re]CR[re]
(;B[qf]CR[qf]
;W[rh]CR[rh]
;B[of]CR[of]
;W[oe]CR[oe]
(;B[og]CR[og]
;W[pg]CR[pg]
;B[ng]CR[ng]
;W[pe]CR[pe]
;B[ne]CR[ne]
;W[nd]CR[nd]
;B[lc]CR[lc]
;W[mb]CR[mb]C[These stones are irrelevant to the life or death problem - white can make two eyes as shown or tenuki and win the semeai later if black captures at n18.])
(;B[pe]CR[pe])
(;B[pg]CR[pg]))
(;B[qe]CR[qe]
;W[rh]CR[rh]))
(;B[re]CR[re]
;W[rf]CR[rf]
;B[qf]CR[qf]
;W[rg]CR[rg]
;B[of]CR[of]
;W[oe]CR[oe]
;B[og]CR[og]
;W[pg]CR[pg]
;B[pe]CR[pe]
;W[ne]CR[ne]
;B[nd]CR[nd]
;W[ng]CR[ng])
(;B[qf]CR[qf]
;W[pe]CR[pe]
;B[sd]CR[sd]
;W[sb]CR[sb]
;B[of]CR[of]
;W[pg]CR[pg]
;B[ng]CR[ng]
;W[oe]CR[oe]
;B[ne]CR[ne]
;W[nd]CR[nd]
;B[qg]CR[qg]
;W[rh]CR[rh])
(;B[of]CR[of]
;W[oe]CR[oe]
(;B[og]CR[og]
;W[qf]CR[qf])
(;B[qf]CR[qf]
;W[qg]CR[qg]
;B[re]CR[re]
;W[rf]CR[rf]
;B[pe]LB[sb:E][sd:D][qe:C][og:A][rg:B]CR[pe]C[RIGHT
Ko is the best you can get. Next white A, black B, white takes the ko at C and black starts with a local ko threat at D or E.])))