The New Sudoku Players' Forum

[GONGORA]

MCC! HI! WHERE ARE YOU? YOU POSTED AT 6pm SAT... I'VE GOT 11am ON SAT... COSTA RICA, CENTRAL AMERICA... I DUNNO AT WHAT REAL TIME YOU POSTED MESSAGE! BUT A MINMIMUM OF 7 HOURS SEPARATE US... NEW ZEALAND?... SWIMMING IN THE PACIFIC OCEAN NEAR POLYNESIA?... OR KAMCHATKA?

I'VE BEEN BATTLING WITH A PUZZLE IN WHICH, AFTER FINDING ONLY ONE "LOGIC ONLY PLACE" FOR A CERTAIN NUMBER, I HAVE NOT FOUND A SECOND ONE! THERE ARE TWO POSSIBILITIES: A) I MADE A MISTAKE IN THE ASSUMPTIONS PENCILED.... B) THIS IS MY FIRST PUZZLE WHERE YOU'LL HAVE TO TRY WHAT YOU JUST DESCRIBED AS A T&E WITH ONE OF TWO OPTIONS... AND GO ALL THE WAY TILL YOU EITHER SOLVE PUZZLE... OR FIND ALL OTHER PATHS AS "IMPOSSIBLE or ILLOGICAL".

(OR MAYBE I HAVEN'T SEEN THE CORRECT WAY AND THERE IS A THIRD ALTERNATIVE?). FOR ILLUSTRATION, THE PUZZLE

My brain has gone on holiday and has taken a passport so it my be away for some time.

But in the meantime, using what's left.

Choosing a candidate from a bifurcate (or multifurcate?) position that leads to a solution, is a guess, with the proviso that the solver stops looking for another solution.

If the solver undertakes to look at the other candidate/s and their pathway/s and so therefore prove that the original choice was the only and therefore logical choice to make, then it can be called T&E.

It is also T&E if there are multiple solutions, so long, as ALL pathways are checked.

Just a thought.
If ALL pathways are not checked is it still a guess :?:

WITHOUT THE "ONLY ONE NUMBER I FOUND A PLACE FOR"..

WILL SEE IF YOU ARE AWAKE SOON... OR IF ANYBODY ELSE WANTS TO SOLVE IT AND FIND A LOGICAL PATH OVERSEEN AT THE MOMENT... CHAU!

[emm]

Hi Gongora

You're right - what the heck about the caps. (Old Spanish speaking gentlemen can get away with murder!)

I'm not sure how you're trying to post the puzzle but it isn't coming though. Are you able to send it in a grid like this

1 * * * * * * * *
* * 2 * * * 3 * *
* * * * 4 * * * *

* * * * * 5 * * *
* * * * * * * * *
* 6 * * * * * * *

* * * * * * * * *
* * * * 7 * * * *
* 8 * * * * * * 9

where you place a number where there's a clue and a * where there's not?

I'm sure we can help.

[emm]

Hi MCC, I think we have ourselves a bifurcation thread here!

What we’re trying to do is nail down a definitive once-and-for-all statement for what we mean by guess. And we have agreement!

If you accept one candidate without a logical reason simply because it works and without trialling for others then you’re guessing. Sounds so obvious doesn't it!

Do we even need to consider logical T & E bifurcation strategies? You can’t do just one chain and leave it at that - they require a proof by contradiction, don't they?


Edit : Re your comment on T & E and multiple solutions, I'm still waiting for an answer to this one

can anyone produce a puzzle that is not solvable by logic and has one solution?

patiently yours

[GONGORA]

HI, EVERYBODY! VERY OLD, OLDMAN IS BACK... & GLAD TO SEE MANY HAVE COME TO RESCUE!

CONTINUIG WITH SAID PUZZLE... HERE IT IS...

000 | 807 | 001
000 | 000 | 009
020 | 196 | 050
---------------------
085 | 001 | 902
000 | 000 | 000
901 | 200 | 780
---------------------
070 | 518 | 030
300 | 000 | 000
500 | 602 | 000

AS SAID BEFORE, WORKING ON IT I FOUND ONLY "ONEONLY" PLACE FOR A NUMBER... AND WORKED A LOT AFTERWARDS TILL I FINISHED PENCILIN (JOTTING POSSIBILITIES IN EACH EMPTY SPACE) AND ENDED UP WITH NO MORE "ONLYONEs"... JUST THREE OR FOUR "DOUBLE POSSBLTS" AND A FEW "TRIPLE's"... WANNA GIVE IT A TRY? I'LL DEFINITIVELY WORK ON IT SOON...

BY THE WAY, HAS ANYONE EDITED A DICTIONARY TO DESCRIBE SITUATIONS AND END UP WITH A SUDOKU LINGO?

IT WOULD HELP WITH THE "ONEONLY"... "ONLYONEs"... "DOUBLE POSSBLTS"... "TRIPLE's"... ETC???

CHAU TO ALL!

[GONGORA]

SORRY, em... I HAD NOT SEEN YOUR GRID... DO YOU PREFERR THE ONE I SENT, WHERE "0" IS AN EMPTY SPACE?

PS : I'm still waiting for an answer to this one
em wrote:
can anyone produce a puzzle that is not solvable by logic and has one solution? NOT ME! BUT I GUESS IF YOU GET A SOLVED PUZZLE, ELIMINATE 70% APROX OF NUMBERS... THE GUYS THAT LOOK FOR LOGIC MIGHT END IN AN ASSYLUM! AT LEAST I ALLWAYS THINK UNSOLVED PUBLISHED PUZZLES ARE COMPUTER GENERATED! TRUE?

[GONGORA]

HI, YE ALL!

BY THE WAY, THE PUZZLED I JUST PLUGGED IN IS A MEDIUM DIFFICULTY... TODAY'S NEWSPAPER PUBLISHED IN COSTA RICA... A POSSIBLE EXAMPLE OF (WHAT I THINK) A PUZZLE WHERE YOU CAN ONLY FIND ONE "ONEONLYPLACEFORANONLYNUMBER"... ALL I COULD DO, TRYING TO FIND A SECOND "ONEONLYPLACE" I ONLY FILLED ALL EMPTY SPACES WITH A COUPLE OF "ONLYTHESETWONUMBERSHERE" AND A COUPLE OF "ONLYTHREENUMBERSHERE"... AND MANY "MANYNUMBERSHERE"... AM I WRONG? CHAU!

P.S.: em, IS IT 7:45pm RIGHT NOW IN YOUR PLACE? WHERE?

[emm]

Hi again Gongora

Thanks for posting the grid.

In row 5 there is only one place for an 8 – it has to go in row 5 column 5. Then there is only one possible place for a 3 in row 9 – it has to go there. Same in row 4. These are called hidden singles because there are other possible candidates for the cell, but no other possible place for that number.

Then there is a naked single in row 2 – it’s the 4 which is the only possible candidate for one cell. See how you go from there.

A lot of the basic terms are described in Basic Terms and Simple Sudoku.

Let us know if you're still stuck.

[GONGORA]

em! YOU MADE MY DAY! ...AND I AM GRINNINGLY ASHAMED! ...I HAD THE ROW 9 THREE... AND DID OVERLOOKED IT! (OK SPELLING?)...

BESIDES... TWO GREAT TIPS! THE SUDOKU LINGO HAS BEEN DEALT WITH BY BRIGHT - Wayne Gould (Pappocom)! IS HE THE SUDOKU FORUM DAD?

AND THE FREE SUDOKU SOFTWARE FROM SIMPLE SUDOKU! DO YOU RECCOMEND BE DOWNLOADING IT?

I'LL TRY SOLVING THE PUZZLE DURING LUNCH TIME (IN A FEW MINUTES) WITH MY COUPLE! THANKS!...

and... TO Simes, MCC, lunababy_moonchild (bebeluna in Spanish) (killawawa in Quechua), udosuk (you do suck? I DON’T BELIEVE IT!), lviann11… MY THANKS FOR GETTING OINVOLVED IN HELPING! …REMEMBER THESE ARE MY FIRST DAYS… AND NOW MY DAYS ARE NUMBERED! CHAU!

[GONGORA]

...AND WHERE IS EVERYBODY?

[GONGORA]

OK... EVERYBODY ASLEEP... I DOWNLOADED "SIMPLE SUDOKU" AND THINK IT'D GREAT! IT SHOWED WHERE MY PENCILLIONG KISTAKE WAS... AND I SOLVED THE PUZZLE IN A JIFFY!

COMMENTS... SOVING IT ON SCREEN IS DAMNED TOO EASY! I'VE CHOSEN TO CREATE AN "EXTREME", HAVE IT SHOW ALL CANDIDATES, PRINT IT... AND WORK IT ON PAPER!

YES... YOU GET TO A POINT WHERE YOU WILL NOT FIND UNU¡IQUE CANDIDATES... NOR HIDDEN ONES... AND YOU JUST HAVE TO DO WHAT ONE OF THE GROUP SUGGESTED, CHOOSE ONE, CIRCLE IT AND KEEP GOING AND PENCIL YOUR LIFE OUT... AND ENJOY IT!

HAVE A GREAT WEEKEND... WILL COME BACK AND SEE OIF ANY POSTED ANYTHING... CHAU!

[Pappocom]

Hello Gongorra.

Please do not write your posts in capitals. Just to let you know that any future posts written in capitals will be removed from the site.

- Wayne

[GONGORA]

sorry wayne... will keep away not to bother...

[GONGORA]

em…

hi! My pleasure too! …and thanks for great quality help… I wonder why do you like to preserve anonymity? … in my case I am an extroverted maniac! …that’s why I like travelling… visited 92 countries in the world! New Zealand too! Flew from australia… I visited the lower south island… christchurch… whale watching… train to the other side of the island… beautiful sights! Impressive community!

Too much sudoku kept me away from too many responsabilities… too many workers to keep in control… I raise marine water shrimp in huge ponds… and gotta be alwert!

Besides, I got hit on my knuckles a few minutes ago! Had forgotten how it feels. Didn’t like it! …don’t think i’ll be back here… So in case you wanna direct mail me, if allowed here… do so to: GONGORA@GONGORA.ORG and will be glad to keep corresponding… meantime, best of luck and lots of accomplishments. Chau!

[MCC]

MCC! HI! WHERE ARE YOU?

London
Time is about 14:45

... SWIMMING IN THE PACIFIC OCEAN NEAR POLYNESIA?... OR KAMCHATKA?

More like the River Thames, but it's not recommended.

[MCC]

Hi MCC, I think we have ourselves a bifurcation thread here!

Yes we do.

What we’re trying to do is nail down a definitive once-and-for-all statement for what we mean by guess. And we have agreement!

Yes we have.

If you accept one candidate without a logical reason simply because it works and without trialling for others then you’re guessing. Sounds so obvious doesn't it!

Yes it does.

Do we even need to consider logical T & E bifurcation strategies?

Not really.

You can’t do just one chain and leave it at that - they require a proof by contradiction, don't they?

They do.

I have an amendment to the above and that is: that your first guess leads to a deadend or contradiction, then the guess becomes T&E, that's because you can eliminate that particular candidate leaving the other candidate as the only logical option.

Edit : Re your comment on T & E and multiple solutions, I'm still waiting for an answer to this one

can anyone produce a puzzle that is not solvable by logic and has one solution?

patiently yours

What you are saying here em, is that you want a puzzle that has a bifurcation at every step, and taking a guess at each step which candidate to use, leads to a complete solution without retracing your step, so that the whole puzzle is a guess from start to finish.
I'll let some else take up your challenge.