Finishing More Extreme 200


This post continues, slicing the 9 patterns of More Extreme 200, and conducting trials of the divided sets. A brief, but decisive cluster merge ends the struggle.

Antoine was right. #200 is outstanding. Following a pink/olive analysis on the 9 patterns, I suggested you try another one on the remaining 9 patterns, with 9r2c6 shaded pink. Here is my division, with two pink patterns with one clue, and three olive patterns and one clue. A pink trial throws out five, and the olive trial, three.

more 200 pink olive 2more 200 2nd pink trialIt’s generally best to try the more decisive side, because you want the trial to come to a conclusion, positive or negative. In the pink trial, the remote pair =>9r1c8, E3 => SEnt278 =>r9np36 =>SE8, removing all 8 from c8.

 

 

 

 

more 200 guardianAs we install the olive pattern set, the remote pairs seen in the pink trials come back to haunt # 200. The removal of 9r1c8 allows 3r6c8 to produce five 5 conjugate pairs in a loop, and therefore odd sided slink loops in 7 and 8, making a solution impossible. This also confirms 3r7c8 as a necessary guardian.

 

 

more 200 collapse trThe final collapse unravels a curtain of naked pairs which explain why #200 was so extraordinarily tough.

Let’s close the review with a round of applause for Antoine Alary. Wear your helmet, my man.

Next I’m going tackle the extremely tough, but popular, Weekly Extreme Competition series, at www.sudoku.uk . My review puzzles start with #426 and end with #435. All of the puzzles are available, packaged with their solutions, in an archive table on the competition site. The competition is to complete each puzzle within a week, and key in the solution to the site before the midnight deadline. Winners over the whole year get their names on the honors list.

I hope Weekly Extreme competitors will follow my posts, and comment on them. If you know any, let them know about it. Of course, we will always be seeking humanly efficient, entirely logic based route to the solution, which is not the only way to succeed in the competition. But these compeititors are serious Sudoku solvers, and could easily become sysudokies as well.

 

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Taking on More Extreme 200


This post and the next checkpoint a sysudokie solution of Antoine Alary’s extra tough More Extreme 200. Sysudokie readers are given an opportunity to get a little extreme, as well.

Happy St. Patrick’s Day. Let’s do the 200. But first, your kraken analysis homework on More Extreme 144:

more 144 6 krakenYes, the other 6 in the fin box is removed, but the four kraken hostages escape.

The basic solving of More Extreme 200:

more 200 basic tr

more 200 basic gridIt’s a semi –monster all right.

more 200 finned 78-wingThe next result is from the X-panel, and is quite unusual. A simultaneous, finned 7-wing and 8-wing, but no krakens.

That’s all I see for X-panels, coloring or AIC, but the 9-candidates are relatively sparse, with slinks in both directions.

Going to pattern analysis, I have two pink and five olive, with many 9-candidates in one set or the other. A trial of the pink set of patterns could take a big step.

more 200 9 pink olive

more 200 pink trial trIn fact, in the trial of pink patterns, the two 9-candidates in both are confirmed, and the seven exclusive to olive patterns are removed.

As luck would have it, the trial fails with three bv 36 cells in r9. The true 9 pattern is among the olive five

more 200 olive gridThe olive trial brings in only one clue, 9r5c5, but removes two. C9 generates a boxline in S. It’s 3 removals in S allows a Sue de Coq.

 

 

 

 

 

 

 

More 200 SdCThe contents of Sc5 are 3(2+6)(7+8) if 7 and 8 are not both missing and the naked triple236 if they are missing. But the latter generates three bv 36 cells in r9. So the Sue de Coq is verified to contain 3(2+6)(7+8), removing 78r2c5.

Now, how would you like to do the next pink/olive pattern analysis? The remaining 9 patterns can be divided again.

 

To be sure of agreeing with the checkpoint, make 9r2c6 pink and shade the 9 cells accordingly. Two clues are added in the olive trial, but only one in the pink trial, so we do the olive trial first, hoping for a more decisive result. As usual, you have a week. Lay off the Paddy’s day cache.

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Just One More “More Extreme”


This post concludes the Alary More Extreme review puzzles with More 144, Basic marking features a timely naked quad, and advanced solving is another parade of highlights.

more 144 basic trThe basic trace classifies More Extreme 144 as a tough one. I would hate to be faced with the task of starting it with the number scanned candidates. I wouldn’t even want to do it with the grid encrusted with computer generated number scanned candidates. Are you listening, Antoine?

 

more 124 nq gridIf you don’t go through it, I’d like you to see at least the naked quad along the way. Note the long fill strings, loads of candidates, and the few sparse,and therefore promising numbers.

 

 

more 144 fin swordThe bv scan is a bust, but the X-panel offers some promise. The 6-panel delivers a finned swordfish, with one victim in the fin box. All of the kraken victims go free.

Your challenge for the next post is to identify the kraken victims and to show how each of them escapes. A potential victim that sees the fin by any means is eaten by the fish. Forcing chain vision is necessary.

more 144 9-patternsGoing on through the  X-panels, a 9-swordfish deletes all candidates impeding a coloring cluster of two 9-patterns.

If you don’t see the swordfish, look for its victims now missing from the previous grid.

These patterns extend the coloring into the 6-panel. What happens then is LPO magic.

 

 

more 144 6 LPOOne of the two 9 patterns is true. Together, they limit the blue or the green patterns of other numbers. The limits go both ways. The partial 6-patterns allow two blue 6-patterns, and zero 6-green patterns, with freeforms from the left. It’s a pink/olive wrap, in blue and green! Green candidates, and others orphaned by the blue patterns, are eliminated. That’s nine 6-candidates gone!

 

 

more 144 blue ntThe surviving grid sports a naked triple forcing 8r6c1, a fatal wound. If you care to follow it, the autopsy report is below.

It’s time to close the review. Again, I do enthusiastically endorse Antoine Alary’s Extreme Sudoku and More Extreme sequel for advanced level sysudokies.

 

 

It would be nice if we could can the wild claims and honor  good advanced level Sudoku books for what they are.

more 144 autopsy

OK, a promise is a promise. Next time you can compare notes with me on a sysudokie solution of More Extreme 200. You have yours all ready, don’t you? If not, get the book and get busy!

And don’t forget to do your More Extreme 144 kraken homework. Virginia is in high school now, so I had to do the kraken analysis myself. Fortunately the ©Word X-panel template makes it sooo easy. Just copy the numbers in, delete the ones seen by a true victim and it’s confirmed cohorts, and see if the fin survives.

Yeah, I know.  Virginia says that laptops and Office aren’t cool anymore.

 

 

 

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Smooth Navigation in Rocky Terrain


This post reports a sysudokie attack on Alary’s More Extreme 84 with several highlight eliminations. A naked triple and a combination X-panel punch on the tightly linked numbers lead to a polarity ANL, color bridging and a surprising color wrap. Sounds good?

more 84 basic gridMore Extreme 84 is grudging, if not downright stingy, in basic solving.

An interesting event is the naked triple 459 in the West box . It forced 9 marks before the box was marked to produce them. The c2 removal came from the more 84 basic trresulting NWc2 boxline.

The basic trace:

 

 

 

 

 

more 84 finned sword anl

Once in a while an elimination can be credited to either of two advanced methods.

A finned swordfish and a 2-chain ANL share victims on the 2-panel. The swordfish eliminates the victim because it is in the fin box. There is even an alternate chain on the ANL.

 

More 84 freeformsNext, the 4-panel slinks call for 4 coloring. Winks in r3 and c9 limit the cluster. One of the colors is surely true, and freeforms drawn from the left through the cluster candidates identify only one blue and one green pattern, and orphan 4r3c9, extending the cluster over all 4-candidates.

A remarkably simple and effective application of pattern analysis to coloring.

There are two ways to explain what happens next, when the AIC hinges are marked.

More 84 two shct ANLThe hinges allow a blue and a green 4 to get on the 2 network. The slink between any blue and green candidates in the cluster completes the all black ANL removing cr3c6, and the red dashed ANL removing 2 r6c6. That’s my shortcut ANL.

Another interpretation is that each of the two candidates use forcing chains to see both a blue and a green candidate, one of which must be true. Since the Bob Hanson review, I’ve been calling that a polarity ANL.

more 84 bridgeElegant as that is, it does not solve More Extreme 84. Fortunately I have the slinks to add a red/orange cluster, and it produces some classic bridging.

Cells r1c9 and r3c5 assert

not(green and red), implying blue or orange,

Cell r9c2 then traps 1, 5 and 7 but also asserts

not (blue and orange), implying green or red.

So its (blue and red) or (green and orange).

My trial trace finds that (blue and red) wipes out all 9s from box C. That leaves (green and orange) to wipe out this gem.It looks like More Extreme 84 was custom composed for Sysudoku. I’d sure like to know how much of this analysis Antoine anticipated when he came up with it.

More Extreme 144Just one more review puzzle, More Extreme 144 shown here, and then we’ll do our version of Antoine’s challenge special, #200.

I hope you have your copy and are about ready to compare some sysudokie notes with me.

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Alary at His Stingiest


This post details the solving of the Antoine Alary review puzzle More Extreme 104, featuring a laborious line marking leading to a sea of candidates. Then the day is saved by Antoine’s escape hatch, maintaining a reasonably advanced level of the collection.

The bypass has some success, but Whew! The 2-D trace of line marking doesn’t remotely do justice to the effort involved.

more 104 basic trSo if you passed up the homework assignment, here is what you avoided:

more 104 BML gridBut even here, the efficiencies of Sysudoku line marking make it much less work than traditional number scanning. If you aren’t convinced, here are some line marking pointers: Go back through it, and this time, form the next long line string from the previous one, by deleting the new clue numbers, and typing back in the old ones. On really long strings (6f, 7f!, 8f!!), after copying the line string, delete the numbers seen from the cell before inserting the copy into the cell.

Oh, you’re doing this by hand? You’re not using my ©PowerPoint template? No wonder you’re thinking of tossing Alary’s book into the round file. Don’t do it, Pilgrim! Look at the Tools page. Send the email. Get the template file, it’s free. You can thank me later.

more 104 ANLYes, its horrible. But there’s the upside. It’s easy to dismiss the possibilities of Sue de Coq, APE, or UR rectangles. From line marking I remember marking more slinks for 6 than any other number, so I try fill in the 6-panel first, and notice an almost nice loop.

 

 

 

more 104 nt gridMarking from the NE6 clue, a slow collapse includes two naked triples.

The collapse continues without hesitation, undeterred by the large number of candidates in many cells.

 

 

 

 

more 104 collapse trMy impression is, that if this doesn’t happen in an Alary stingy, you have probably missed the advanced technique eliminations that Antoine built the puzzle around.

 

 

 

 

more 84OK, are you willing to stand up to another Alary stingy pants? This one, More Extreme 84, gets into some really extreme stuff, but basic solving is merely challenging. With the free template and your sysudokie technique, it’s a snap.

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A Little More Extreme


Here is a follow up on the advanced level More Extreme 4, with background looks at the bv map, XYZ map, and X-panel . There is a challenge to find a forcing chain XYZ alongside a regular one.

Entering the bv scan with the More Extreme 4 line marked grid of the last post, we were short of candidates or bv on every Sue de Coq or APE chute, but the XYZ map made up for it.

more 4 bvHere it is shown with several rejected hinges, and two live ones. There is a regular 347-wing and an irregular one constructed with a forcing chain. Both have victims. If you did not find them, jump back to the line marked grid, and take a shot, with the hinges and wings shown here. I’m placing the grid marking of these wings after the other eliminations, but don’t peek.

more 4 fishGoing to the 3-panel after the wings, we catch either a swordfish or a complementary jelly fish, depending on where your net landed. They have the same four victims.

 

 

 

 

 

more 4 XY railNow if you haven’t done it already, you can verify that the fish victims enable us to draw this XY rail, the first one available. On the grid, the slink ending 7-candidates are a toxic set, removing 7r5c3.

But neither that removal, nor the new bv it creates, seems to matter.

 

more 4 3slinksInstead, the more decisive result from the fish attack is the network of strong links among the remaining 3-candidates. The 3-chain analysis yields nothing more. Unfortunately, the octagonal loop is closed with two adjacent winks.

However the long slink chain is a strong asset in Medusa  coloring.

 

 

more 4 AICThe blue/green cluster produces nothing immediately, but when the AIC hinges are added,an AIC chain is found for a strong link between blue 3r5c8 and 3r4c5, extending the cluster by making 3r4c5 green.

Did that one get by you? It’s just putting together what we already know. The chain says that if 3r5c8 is false, then 3r6c7, 9r6c1, 5r4c1 and 3r4c5 are all true. That’s the definition of a strong link! And slinks are the building blocks of Medusa clusters.

Please note, T&E worry warts, there is no assertion here that 3r5c8 is false. Nor is there any test of its falseness. There’s only a demonstration that a remote slink exists. Fortunately, that slink extends the cluster into a wrap. Two green 3s wind up in c5 and in the C box. For that reason, the green army is false, and the blue army, including 3r5c8, is true. More Extreme 4 collapses in a heap.

more 4 XYZsOK, you didn’t peek and you found at least one of the XYZ-wings. Right?

The regular orange 347-wing hinged at r4c5 eliminates 7r4c6.

In the burnt orange 347-wing hinged at r1c1 is something else. The 37 wing is sees the hinge 3 by forcing chain. One victim sees the toxic set by unit winks, but 7r5c1 needs a grouped forcing chain to bow out.

Show this to your Sudoku friends. So far the forcing chain XYZ-wing is a Sysudoku exclusive despite numerous posts demonstrating it.

More 104That was fun, but I want you also to experience the misery of line marking one of Alary’s stingies. Not that number scanning is any easier. For this mission, should you accept it, the assignment is More Extreme 104. Your 17 clues have just arrived. In the sea of candidates, there is a lifeboat. If you lose it in the fog, I’ll send the Coast Guard next post.

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More Extreme?


Here we begin a review of the second collection of Antoine Alary’s Extreme series, with general comments, a review table, and a checkpoint on the Sysudoku solving on More Extreme 64, a puzzle that is typical of the “generous” variety of Alary puzzles.

Antoine Alary has published two puzzle books under his own name, claiming each to contain “200 of the toughest Sudoku puzzles known to man.” My review differs with this brash claim, but more importantly, it discloses Antoine’s rather unique approach to composing. It’s ambitious and unique, in keeping with the daring Antoine of the back cover, a mathematical logician electronic designer immersed in razor edge sports such as “snowboarding, wakeboarding and mushroom hunting”. You scare me, man.

As usual for the review, I preselected 10 of the 200 puzzles, tracing my solving process with 2-D traces and significant grids. My selection was every 20th puzzle, starting with More Extreme 4. I hope you were successfully introduced to the collection via More Extreme 64, which is represented in the review table. For conventions of the table, see the Reviews page.

More Extreme Table

The table makes clear that Antoine’s claim of “toughest known to man” is a bit overblown, but his puzzles are consistently advanced level. Two invoked a touch ofpattern analysis on my part, but no trials of any kind were required. Among my reviewed collections, KrazyDad’s Insane collection appears to be significantly tougher. And then there’s the established monsters, including two mounted in the Sysudoku trophy room.

This review table is the first featuring the bypass (DB) phase of box marking. I had solved the puzzles before adopting the bypass, and could therefore compare the numbers of box marking clues I found with and without it. In the table, box marking results without the bypass are written below with it. For sure I did better with it, making line marking easier. But in all cases, the final basic solving candidate field after line marking was the same. Only the line marking results with the bypass are included.

Sysudokie readers might be wondering why the number of given clues is omitted from the review table. It’s because it is always the same number, 17. Antoine’s mathematical logic professor may have required him to study the proof that 17 is the minimum number, and in scholarly daring, he has taken this on as a trademark of his puzzles. I can report that, as a composer, Alary consistently provides a route to the solution, which is no small accomplishment with this uniquely limited number of givens.

My bottom line is that my sysudokie readers can well invest in these books. I now have them both, on the strength of the second one, the subject of this review, entitled More Extreme Sudoku, © 2011. The first, Extreme Sudoku, apparently came out in 2010. I don’t understand how I missed it, so I’ll just blame it on Tom Sheldon, Andrew Stuart, Paul Stevens, Will Shortz, SudokuOne, KrazyDad, Max Pitkow, Bob Hanson and Wayne Gould.

In fact, when you get your copy, solve More Extreme 200, the puzzle Antoine singles out as the collection’s toughest. I didn’t want to include the standout toughest in the review, but I will post a checkpoint for you immediately after it. Be prepared for the worst, or best, depending on you.

More 64 DB trThe More 64 bypass trace is typical, with long chains of clues on two numbers. I’m quite pleased that the bypass experience. Miss the path and you are often overwhelmed with candidates.

Speaking of being overwhelmed with candidates, I was annoyed that Antoine includes all number scanned candidates in a keypad format on half of his puzzles. You have to wonder if any Sudoku publication outside of this blog will ever acknowledge the redundancy of keypad marking, and adopt something more useful.

Antoine is excused, though, because his Extreme Sudoku pre-dates the early Sysudoku posts on slink marking, but I do hope that his later editions and collections drop this “helpful” feature. It may be that a good part of the difficulty attributed to his puzzles is just having to get the basic solving done with a minimum of givens, and an inferior starting method. To my way of thinking, providing the candidates, or doing it by computer, is not the answer.

The DB and Box columns of the table divide the collection on basic solving. Puzzles 64 and 184 are especially generous in box marking, while 104, 144, and 164 are downright stingy. Not many clues are added in line marking. We’ll see how this plays out in several puzzles checkpointed in detail, first with the very generous More Extreme 64. The bypass hit two numbers 3 and 9 hard, and the run continued on 9 in slink marking.

More 64 BM tr

More 64 578 wingLine marking is easy, and the resulting grid is liberally populated with slinks and bv, strongly suggesting Medusa coloring . But if you go to your bv map, you are rewarded with a regular 578-wing. The more advanced part is that the victim sees one of the three toxic candidates by forcing chain.

 

 

 

More 64 coloringOr if you happen to miss the XYZ-wing forcing chain, when you get to coloring, you get an easy wrap with two green 8-candidates in c6. In either case, the collapse is immediate.

Let’s do another one.

In the review table, More Extreme 4 rivals a Frank Longo Absolute Nasty IV, or a CrazyDad SuperTough.

 

 

More 4 LMIt starts easily and is also basically generous, but it calls for some advanced artillery.  You can lift out the original clues, do box marking and line marking if you like. From here, see if your advanced solving confirms that review table line. I’ll checkpoint you next post.

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