## Solver says Forcing Chain... is there another way?

Post the puzzle or solving technique that's causing you trouble and someone will help

### Solver says Forcing Chain... is there another way?

The original:
Code: Select all
`6..|...|7..2..|..8|.....3|9..|..5---+---+---1..|...|4...8.|3.2|.9...5|...|..6---+---+---4..|..1|2.....|7..|..3..9|...|..7`

At the stuck state:
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`6     9     14    |  24    5     3     |  7     128   282     5     17    |  16    167   8     |  9     3     48     147   3     |  9     127   47    |  16    126   5------------------+--------------------+------------------1     3     26    |  568   6789  569   |  4     278   287     8     46    |  3     46    2     |  5     9     19     24    5     |  18    178   47    |  3     278   6------------------+--------------------+------------------4     67    78    |  568   3     1     |  2     56    95     126   128   |  7     4689  69    |  168   146   33     16    9     |  24    2468  56    |  168   1456  7`

The built-in solver (not my implementation) suggests a Forcing Chain as the next step, specifically [R1C3] -4- [R5C3] -6- [R4C3] -2- [R4C9] -8- [R1C9] -2- [R1C4] -4- [R1C3].

To me, this feels like making a guess, and so I'm not happy with using it, but I'm having trouble locating any other way to progress in this puzzle. Any suggestions?
EnderGT

Posts: 69
Joined: 19 February 2008

Lot's of chains and some ALS, for example:
Almost Locked Set XZ-Rule: A=[r6c4568] - {12478}, B=[r2c45],[r3c56] - {12467}, X=4, Z=2 => [r3c8]<>2
hobiwan
2012 Supporter

Posts: 321
Joined: 16 January 2008
Location: Klagenfurt

hobiwan wrote:Lot's of chains and some ALS, for example:
Almost Locked Set XZ-Rule: A=[r6c4568] - {12478}, B=[r2c45],[r3c56] - {12467}, X=4, Z=2 => [r3c8]<>2

Yeah, I ended up finding an XY-Chain that did the same thing the suggested Forcing Chain did. Specifically, R1C4 and R5C3 are linked to remove the 4 from R1C3.
EnderGT

Posts: 69
Joined: 19 February 2008