Kraken Fish Invade Hodoku’s Pond


This post starts with a homework checkpoint on single fin kraken analysis, via the blank line tally and suset scratchpad. The homework demonstrates an essential technique for finned fish that is missing from Hodoku. Then these sysudokie techniques find additional kraken victims in Hodoku finned/sashimi examples.

Your homework assignment was a grueling kraken analysis. On the left panel, I took on row 3 candidates when I realized that all three had a route through c3 (t’s) to implying candidates in row 6, wiping out c9 rivals of SE rival of the fin. The r4c2 victim joins this party. Two r6 potential victims also wipe out the same two c9 rivals of r9c9. 8r6c7 implies the fin, and is saved. 8r9c1 implies the fin via the r8 group forcing chain. Suspect r4c1 sees the fin via the c1 group to r8c2 chain, and is removed. Every one of these chicken scratchies is needed!

Hodoku Franken 2

The second 1259/12579 finned jelly works on the remaining suspects. r6c7 is now betrayed by the chain that saved it before, because the fin changed. New suspects r8c12 confirm the fin and are prevented from “seeing” it.

Noticed that “saved” means saved from the fish under analysis. It doesn’t mean true. Another fish may get this worm. But if it is not saved from a particular finned fish, it is false. It is not going to be in the solution.

The point of this challenge is the potency of kraken analysis. The puzzle was composed to illustrate the extreme Mutant or Franken fish, but it collapses well before the end of this advanced level analysis of a finned jellyfish.

On the finned fish page, Hobiger follows other human solving advisers of the time, and considers only the box fin victims. Both of his finned/sashimi examples have extra kraken victims, easily revealed by the suset scratchpad.

In the first example, the row wise scratchpad list reads:

2/38, 9/14, 7/134, 1/269, 3/256, 4/139, 5/2568, 29/1348, 24/2389, 79/134, 49/1349, 47/1349, 35/2568, 479/1349, 279/1348, 2479/13489

It reveals Susets 79/134, 279/1348, and 479/1349 ahead of the Hodoku boxfin jelly example of 2479/13489. The underlines identify the cover set of the fin, the columns in this case.

Hodoku finned jelly

Hodoku’s finned jellyfish is revealed to be a sashimi swordfish also, and a finned swordfish making an additional elimination.

Hodoku Finned 3In the second Hodoku finned jellyfish example, the suset 1469/12389, with fin in column 3, produces only the fin box eliminations. All kraken potentials confirm the fin.

 

However, a sashimi jellyfish with the fin in column 9 is defined by the suset 1469/12389. It produces a SE box fin elimination and two kraken victims.

 

Hodoku Finned 4Of course, the eliminations of either choice would destroy the other, but clearly, in a difficult case, you would want to explore kraken opportunities beyond the box fin.

But there is still more to learn from this example.

Look at the suset 146/1289. Could it possibly define two finned fish with two different fins of two cells each? Check it out.

 

Actually, Hodoku has this covered, in a way. Hobiger quotes the governing rule for the kraken analysis of finned fish as:

“In a finned fish all possible eliminations that see all of the fins can be eliminated.”

But as this post has demonstrated, Hobiger applies a limited definition of “seeing” to single cell fins. On the Last Resorts page, Hodoku presents rather extreme examples of full vision kraken analysis to multiple fins. Next time, we examine these, and checkpoint the multiple fins that Hodoku ignores in his second finned jellyfish example, that you can find with your suset flashlight. Happy hunting!

 

 

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About Sudent

My real name is John Welch. I'm a happily married, retired professor (computer engineering), timeshare traveling, marathon running father of 3 wonderful daughters and granddad to 7 fabulous grandchildren. The blog is about Sudoku solving. It covers how to start, basic solving to find candidates efficiently, and advanced solving methods in an efficient order of battle. It is about human solving methods, not computer solving.
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