... by: Yves

E9=5 C7=4 E3=9 B8=8 J4=5 J2=6 J6=9 B3=2 J5=8 D9=3 C9=7 F4=8 J9=1 D7=8 H5=1 D5=5 G5=6 (E9=5)

Each node(x) in this list, with the next node(x+1) is a trivial solution to this #709.

Example:
E9 = 5 and C7 = 4
C7 = 4 and E3 = 9

... by: Serban

# 709 Basics to 23
1. H5=1 & J5=8 solve
2. A9=2 & J5=8 solve
3. D9=3 & C9=7 solve
4. J4=5 & J5=8 solve
5. G5=6 & J5=8 solve
6. C9=7 & J5=8 solve

... by: Norman Powell

Unsolvable with deterministic methods, one use of Bowman's Bingo solves. I get many more eliminations using Forcing Network first.
X-Cycles: Eliminate 3 from H6 since it can see both ends of a chain.
Forcing Networks 1st Pass:
Eliminate 4 from B5, 1 from C4, 4 from C4, 4 from C6, 5 from E5, 1 from H1.
Forcing Networks 2nd Pass:
Eliminate 1 from A9, 9 from B6, 1 from C6, 1 from D5, 5 from H6, 5 from J6
Forcing Networks 3rd Pass:
Eliminate 2 from A7, 5 from H4
Forcing Networks 4th Pass:
Eliminate 2 from E9, 2 from H9, 2 from J9
Bowman's Bingo: Eliminate 2 from A3 after 20 trials over 6 Levels of trial guesses.
Solved A3 as 7
Hidden Singles: Row A, A9=2, Row E, E5=7, Row F, F1=7
WXYZ-Wing: Hinge E9, Corners E3, B9, D9 Constrained Values 3, 9, 6
Eliminated Unconstrained Value 5 from Cell E7
Solved E8 = 2
Hidden Single Row D, D6=2
Confined to Box: Value 1 is confined to Row D and Box 4, Eliminate 1's from elsewhere in Row D or Box 4.
Subset Exclusion: Pair H9 & J9 - Pair of Cells can see value 5
Locked Set Cells B9, D9, E9 excludes Values 9
Locked Set Cells H8, G8 excludes Value 1
Eliminate 5 from H9
Confined to Box: 5 is confined to Row H and Box 9 Eliminate from other areas of Row H and Box 9.
Hidden Triplets in Row J for Values 5, 6, 8 in Cells J2, J4 and J5, eliminate other values in those Cells.
WXYZ-Wing Hinge F4 Corners F6, C4, J4 constrained Values 1 8 6
Eliminate unconstrained value 5 from Cell E4.
Solved Cell: E4 = 4
WXYZ-Wing Hinge D9 Corners D5, D7 B9 Constrained Values 5 6 8
Eliminate 3 from E9
WXYZ-Wing Hinge F7 Corners F4, C4, J4 Constrained Values 8 9 1
Eliminate 5 from F8
Hidden Singles: Column 8 H8 = 5, Column 1 H1 = 3, Row E, E2 = 3
Confined to Box:
9 is confined to Column 3 and Box 4, eliminate other 9's in Column 3 or Box 4
4 is confined to Row G and Box 9, eliminate other 4's in Row G or Box 9
Rectangular Elimination 9 On in Cell G5 and Strong ling B5 and B1 would eliminate all the 9's from Box 7 so eliminate.
XY-Cycle: 1 in F4 can see both ends of chain, so eliminate.
Hidden Singles: Box 2, B5 = 9, Column 6, C6 = 5, Row F F6 = 1
Solved Cell: C4 = 6
Hidden pair in Box 6 for values 5 9 in Cells E9 F7, eliminate other values in those cells
Hidden pair in Column 9 for values 3 6 in cells B9 and D9, eliminate other values in those cells.
Solved Cells: F7 = 9, E9 = 5, D3 =9
Naked Pair in Column 4 for Values 5 & 8 in Cells F4 and J4, eliminate values 5 & 8 from other cells in Column 4.
X-Cycle: Value 8 in F7 has weak links to both ends of chain eliminate.
16 Solved Cells and Hidden Singles
Y-Wing: Hinge H3, Corners D3 and J2 Constrained Values 1 & 8
Eliminate unconstrained Value 6 from cells D2 and G3.
The remainder Solved Cells and Hidden Singles

... by: Dieter

#709 - initially populated cells: 23 = 28,4 %
No solver used, solver = brain.

Strategy: numbers 3,5,6,7,8 occur most frequently, combine two cells with almost same candidates.
combinations of D7 = (2,3,8) and D9 = (2,3,5,6)
after basic checks 4 matrices left: 3/5, 3/6, 8/3 and 8/5
D7=8 & D9=3 solve with J2=6.

Optimization:
D9=3 & J2=6 solve.

... by: Serban

# 709 Basics to 23

1. D9=3 & G5=6 solve

2. D9=3 & J5=8 solve

3. J6=9 & J5=8 solve