Pattern-Based Constraint Satisfaction and Logic Puzzles
(Second Edition)

Denis Berthier



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Errata



Errors in the first edition, corrected in the second:

p. 436, end of first paragraph: delete sentence "However see the next sub-section."
p. 461, section 17.1.2 §4: instead of "W*-braids", read "B*-braids";
p. 475, section 17.4.2 end of §1: instead of "nor enough" read "not enough".



In both editions, two errors have been discovered and corrections have been proposed by Daniel Darroc in the manual solutions of two N-Queens examples (section 5.11):

In the first n-Queens example (section 5.11.2), there is an error in the initial eliminations by ECP: r7c1 should have been been eliminated instead of r6c1.
As a result, the resolution path should be changed to:
whip[1]: c4{r7 .} => ¬r7c3
whip[1]: c3{r4 .} => ¬r6c1
whip[1]: r6{c4 .} => ¬r8c4
whip[2]: r6{c4 c6} – r8{c6 .} => ¬r7c4
singles to the end


In the third n-Queens example (section 5.11.4),a whip[1] elimination has been forgotten after the whip[2]:
whip[1]: r8{c5 .} => ¬r4c1
Also, the first whip[4] has a couple of typos. It should be:
whip[4]: r5{c4 c9} – r4{c8 c6} – r1{c6 c8} – r8{c1 .} => ¬r7c4 (G eliminated)
As a result, the resolution path should be changed to:
whip[1]: r7{c6 .} => ¬r5c6 (A eliminated, whip on light grey cells)
whip[1]: r8{c5 .} => ¬r4c5 (B eliminated, whip on medium grey cells and r8c5)
whip[1]: c5{r2 .} => ¬r5c8 (C eliminated, whip on dark grey cells)
whip[1]: c6{r4 .} => ¬r4c9 (D eliminated)
whip[2]: r5{c9 c4} = r7{c4 .} -> ¬r8c9 (E eliminated)
whip[1]: r8{c5 .} => ¬r4c1
whip[3]: r5{c9 c4} – r2{c1 c5} – r8{c5 .} => ¬r1c9 (F eliminated)
whip[4]: r5{c4 c9} – r4{c8 c6} – r1{c6 c8} – r8{c1 .} => ¬r7c4 (G eliminated)
whip[4]: r5{c9 c4} – r1{c4 c6} – r4{c6 c8} – r7{c8 .} => ¬r2c9 (H eliminated)
singles to the end



In both editions, a typo has been found by Defise, for the example in section 7.7.1. "A puzzle with W=B=7 and gW=2"

The resolution path with braids was not given in PBCS, because the B rating was irrelevant to the point of this example. But as it is mentioned, it should be correct. After running it again, I find B=6



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