... by: Norman Powell

AS's solve makes 26 eliminations before running out of methods, indicated [AS#, Value Row Column, Method] in the following. This puzzle can be solved by Forcing Networks.
Confined to Box Value 9 is confined to Column 8 and Box 9. Eliminate 9A8 [
AS01 9A8 Pointing Pair, Same method different name]
Alt. Inf. Chains Value 9 of Cell D6 has weak links to both ends of the chain, Eliminate.
[AS02 9D6 Forcing Network, I have AIC earlier than FN in the order of methods]
Confined to Box Value 9 is confined to Row 4 and Box 4. Eliminate 9E1
[AS03 9E1 Pointing Pair]
Alt. Inf. Chains Value 8 of Cell A3 has weak links to both ends of the chain
This possibility would cause a contradiction - Eliminate
[AS05 8A3 Forcing Network]
Alt. Inf. Chains Value 8 of Cell J3 has weak links to both ends of the chain
This possibility would cause a contradiction - Eliminate
[AS04 8J3 Forcing Network]
Forcing Network Pass 1:
Possibilities Forced to Same State when Value 8 in Cell B1 is ON or OFF
Eliminate Forced OFF Possibility: Value 7 in Cell E5
[AS07 7E5 Forcing Network]
Eliminate Forced OFF Possibility: Value 3 in Cell E5
[AS06 3E5 Forcing Network]
Eliminate Forced OFF Possibility: Value 7 in Cell B9
[AS09 7B9 3D Medusa]
Eliminate Forced OFF Possibility: Value 3 in Cell B9
[AS08 3B9 3D Medusa, I allow FN to run through finding all possible eliminations before returning to the beginning of the list of methods]
Cause contradictions so eliminate: 8A8, 6A9 [AS10 6A9 Forcing Network],
7A9 [AS19 7A9 Naked Pair], 4B3, 3B9, 7B9, 8D9 [AS18 8D9 Forcing Network],
3E5, 7E5, 7E6 [AS24 7E6 Forcing Networks], 2G3 [AS11 2G3 Forcing Network],
2G6 [AS12 2G6 Forcing Network], 5H3 [AS13 5H3 Forcing Network],
6H3 [AS14 6H3 Forcing Network], 6J7 [AS15 6J7 Pointing Pair],
6J8 [AS16 6J8 Pointing Pair]
Forcing Networks 2nd Pass:
Eliminate: 5D2 [AS23 5D2 Forcing Networks], 7D4 [AS21 7D4 Forcing Networks],
3D8
Solution Found testing subsequent possibilities, the following eliminations found by AS are part of the final eliminations to reach the solution.
[AS17 6D9 Forcing Network]
[AS19 7A9 Naked Pair]
[AS20 8D9 Naked Pair]
[AS22 4B3 Forcing Networks]
[AS23 5D2 Forcing Networks]
[AS24 7E6 Forcing Networks]
[AS25 1H3 Forcing Networks]
[AS26 3D8 Forcing Networks]

... by: Dieter

#716 - initially populated cells: 21 = 25,9 %
No solver used, solver = brain.
basics: %

Strategy: numbers 2,4,8,9 occur most frequently, combine two cells with almost same candidates.
combinations of G1 = (1,2,5,9) and G3 = (1,2,5,8);
after basic checks 4 matrices left: 1/8, 2/8, 9/1 and 9/8
G1=9 & G3=8 solve with F5=3.

Optimization:
F5=3 & G3=8 solve.

... by: Frans Goosens

#716

Combination 2-digits cells

G4=2 No solution, Undo calculation
G4=7 No solution, Undo calculation
H5=3 No solution, Undo calculation
H5=5 ( A9=9 ) Solved,

Total solving time is : 16 sec.
Number of logical steps is : 1904

... by: Serban

# 716 Basics to 21
1. G7=5 & H8=6 solve
2. A8=9 & E8=4 solve
3. G6=7 & J4=3 solve
4. D6=8 & J1=4 solve
5. D6=8 & A1=1 solve
6. D6=8 & F9=6 solve
7. J1=E3=4 OR J1=F8=4 solve