... by: Serban

# 645 A5=4 B8=7 E6=3 Basics to 28

1. Number 3 n=4 e=5 N=12 Nc=3 Ns=1=> any[A1,H2,B7,J9]=3 => basics to 35
Note ; D8=3
1a. W-wing 79 [A4,D5] => DE4<>7 => D5=7 lbasics to 37
1b. X-chain x=6 => [J156,F2,B3,C4,E4,G6]<>6 => F2=8 solve

2. Box 4 ABC456 n=4 e=5 Nc=18 Ns=11 => [ A4=7 OR A6=9] & C4=2 solve

3. Box 5 DEF456 n=4 e=5 Nc=12 Ns=3 => [ F5=6 OR F6=2 ] & E4=9 solve
Note: D5=7

4. Box 7 ABC789 n=4 e=5 Nc=16 Ns=15 => A7=2 & C8=5 solve

... by: BGH

#645 I did not solve this one so I tried other solutions.
Goosen's
Basics 34.6%
Step 1 3 @ A1 (Pair 39, one must be in solution. 9 does not converge) 42%
Step 2 9 @ A6 (Pair 79, one must be in solution. 7 does not converge) 55.6 %
I had to add a step 3
Step 3 1 @ D3 (Pair 14, one must be in solution. Intersection of multiple triples & quadruples)
Convergence.
Dieter's >> No explanation for selecting 1 @ J1 so simple trial & error guess? But it is a solution.
Both solutions were the same results. THX!

... by: Frans Goosens

#645

Combination 2-digits cells

A1=3 ( A6=9 ) Solved,

Total solving time is : 10 sec.
Number of logical steps is : 1235

... by: Billa

Today's puzzle was far easier than usual, rating at 8.9 SER and solving with only ALS-AIC. I'm surprised your solver cannot defeat it. For a couple of months I have been publishing articles with logical solutions (no guesswork) on my blog which I am unable to link due to the site's spam filters but the difference in difficulty is made quite apparent

... by: Dieter

#645 - populated cells = 25 = 30,9%
basics: E6=3, A5=4, B8=7
populated cells: 25 = 30,9%
strategy: try to get hidden pairs or triplets. No solver used.
combinations of J1 = (1,3,4,6) and J4 = (2,6,7) as numbers 1,3,4,7 are populated most.
J1 = 1 solves

... by: Serban

# 645 A5=4 B8=7 E6=3 Basics to 28

1. X-chain : x=1 => [G8,GJ9]<>1; x=3 => J7 <> 3; x=4 => E12 <> 4

2. Number 1 n=3 e=6 N=17 Nc=8 Ns=8 => J1=1 solve

3. Number 9 n=3 e=6 N=20 Nc=12 Ns=11 => E4=9 solve