I really made life difficult for self with 20.s9. Should have played 20.o7 ...

|20.o7 21.n8 22.p5 23.r8 24.m8 25.l9 26.j7 27.m7 28.m4

or

|20.o7 21.r8 22.p5 23.n8 24.m8

nope, the 1st line above doesn't work -- should be

|20.o7 21.n8 22.p5 23.r8 24.m8 25.l9 26.j7 27.m7 28.m2 29.m3 30.n4 31.l5 32.k3 33.j4 34.i4

I recommend skipping directly to |20.p5 in this situation (tilt crossing (p7) to a flanking peg (r6) on an 0:2 opposition (q10:s10))

Thanks very much, Alan

Unfortunately, "(tilt crossing (p7) to a flanking peg (r6) on an 0:2 opposition (q10:s10))" is completely opaque to me -- I haven't a clue as to what it means

I was just trying to communicate the proper generalization for this pattern. In other words, the left side of the board is not a factor here -- if I see the pattern like the right side of the board, the |19.p7 move makes me immediately think 20.p5, as my first choice. Then I check to see if it works with the rest of the board. If it doesn't, I'm probably screwed.