CHAINS for Beginners
Chains on this page are "for beginners" because they originate from a Group 1 or Group 4 [This is due to my habit of methodically searching groups starting with doubles in Group 1, trying next Group 4 below it, then 7, then across, ie. Groups 2, 5, 8, 3, 6, 9. I recommend this orderly way OR equally straight order ... Groups 1...9. The advantage of ANY orderly way is that you don't have to check backwards to find an ENDING or "target" for your chain.]
Given that hint, users may find the chains more quickly. Also, they are not terribly long chains.
PB Post 2014 02 22 Lvl 6 (Repeated lower down)
For Chain Practice, start here:
PB Post 2014 02 22 w22 Same as above, except the gray boxes are filled in.
(Note: Using "simple" methods, the 8 underlined numbers can be removed as choices.)
To proceed, I found a chain beginning with 3 in A2. Then G2, H3, H7. This proves that A7 cannot contain 6, and must equal 9. Finis!
PB Post 2014 02 29 Lvl 6 (Repeated lower down)
For Chain Practice, start here:
PB Post 2014 03 29 Lvl 6 w18 Same as above, except the gray boxes are filled in.
Note: Using "simple" methods, the underlined 5's (G4 and I5) can be removed as choices.
To proceed, a chain was found, beginning with the 5 in B4. Then B9, G9, and G3. This proves that G4 cannot equal 1, and so G4 must equal 9. FINIS!
Here's a partially completed puzzle. Three independent chains can be found that would solve it. One of them is detailed lower down.
1. Begin with 9 in C2. End with 5 in I6. VERY LONG!!
2. Begin with 5 in B5. End with 8 in A7. Pretty long.
3. Begin with 2 in A6. End with 6 in E7
PB Post 2014 05 31 Lvl 6 w31 with doubles circled.
PB Post 2014 05 31 Lvl 6 w31 (5th view) Same as above, except one of the chain paths is shown.
At least two other chains might have been used:
Chain starting with 5 in B5 ending with 8 in A7 proves that B7=9
Chain starting with 2 in A6 ending with 6 in E7 proves that A7=8
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