## 0074: "Binary Sudoku"

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BlueTorch
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### 0074: "Binary Sudoku"

Flashback!
You know, you ended up giving more information than was necessary to solve it. One star?

Shoofle
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There're only two possible binary sudokus, and they are rotations of each other. The minimum amount of information needed to solve it is 1 bit.

xkcd
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You know, you ended up giving more information than was necessary to solve it. One star?

I think the alt-text says it's "medium" difficulty, for this reason. (also because it makes the joke work better :))

Chocobean
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hmm is there already hex sudoku out there?

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One of the papers I receive at work had a mega sudoku in it. It was a regular 9x9, but each corner square was the corner square for another sudoku. It was like five in one! (For example, the top-right 3x3 block of the centre 9x9 square is the bottom-left 3x3 block of another 9x9 square, multiply by all four corners of the centre square).

It took me over an hour to do, excluding working in between, of course.
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Shoofle
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I think someone mentioned that over in logic puzzles, I think it's called samurai sudoku.

une see
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Isn't sudoku just the magic square in math or something? Pretty sure I did this in almost every math program outside of school I ever participated in...Was fun, but mildly frustrating, since I only carry around pens, and not pencils.
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i've seen one that was 36x36 squares instead of 9x9, if i remember correctly.
i was working on it for several hours before i got bored.

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une see wrote:Isn't sudoku just the magic square in math or something? Pretty sure I did this in almost every math program outside of school I ever participated in...Was fun, but mildly frustrating, since I only carry around pens, and not pencils.

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I saw an interesting type of Sudoku in the newspaper the other day. It replaced the numbers with letters, but it also had a darkened section of the puzzle, which, when completed, would fill in the blank of a phrase. The tricky part about this one was that one of the letters wasn't shown in the setup. My brother and I tried to figure out the sentence without bothering to do the puzzle - we decided that the missing letter was E, and one of the blanks was hope, but we couldn't figure out the other blank.
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junes
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### Re: Binary Sudoku

but wouldn't a binary sudoku technically be just one square in which to put a 1, seeing as how the decimal sudoku doesn't include zero... I understand however, that it was important to do it the way it was done for the joke to make sense, but a correct binary sudoku would probably be the easiest puzzle to ever solve- or the most confusing one

Moose Hole
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### Re: Binary Sudoku

junes wrote:but wouldn't a binary sudoku technically be just one square in which to put a 1, seeing as how the decimal sudoku doesn't include zero... I understand however, that it was important to do it the way it was done for the joke to make sense, but a correct binary sudoku would probably be the easiest puzzle to ever solve- or the most confusing one
It's not really decimal sudoku, it's more like (3^2)^2, and the symbols don't really matter. I have seen (2^2)^2 sudoku on childrens' menus at restaurants, and it works fairly well, though it's easy to solve. (1^2)^2 would indeed be a single square; a 2x2 grid isn't a real sudoku form because each of the "box" groups don't contain all the symbols.

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### Re: Binary Sudoku

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### Re: Binary Sudoku

junes wrote:Look at me, I think I'm clever reviving a thread so old RealGrouchy still has notifications for it because I don't realize that Sudoku can use any digits, characters, or figures, not just whole numbers.
Look up the etymology of "binary", and you will find, in some language or another, the roots for "two" and "numbers". 0 and 1 are two numbers (digits).

- RG>
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junes
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### Re: Binary Sudoku

RealGrouchy wrote:
junes wrote:Look at me, I think I'm clever reviving a thread so old RealGrouchy still has notifications for it because I don't realize that Sudoku can use any digits, characters, or figures, not just whole numbers.
Look up the etymology of "binary", and you will find, in some language or another, the roots for "two" and "numbers". 0 and 1 are two numbers (digits).

- RG>

I am very much familiar with the etymology of "binary", latin btw being a grammatical form of the word bi = 2... but i would like to stand by my opinion, that zero simply doesn't belong in a sudoku, for the simple reason, that it's a game of adding numbers. Should you place a zero in a sudoku-block that block would theoretically still be blanc. Thus a sudoku in binary code would be only 1 block.. a binary sudoku in the etymological understanding to which you refer would hold 1 and 2

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### Re: Binary Sudoku

junes wrote:I am very much familiar with the etymology of "binary", latin btw being a grammatical form of the word bi = 2... but i would like to stand by my opinion, that zero simply doesn't belong in a sudoku, for the simple reason, that it's a game of adding numbers. Should you place a zero in a sudoku-block that block would theoretically still be blanc. Thus a sudoku in binary code would be only 1 block.. a binary sudoku in the etymological understanding to which you refer would hold 1 and 2
So it's a balanced ternary sudoku that's ommitting -1/q. Happy?
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CogitoSum
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### Re: Binary Sudoku

junes wrote:
RealGrouchy wrote:
junes wrote:Look at me, I think I'm clever reviving a thread so old RealGrouchy still has notifications for it because I don't realize that Sudoku can use any digits, characters, or figures, not just whole numbers.
Look up the etymology of "binary", and you will find, in some language or another, the roots for "two" and "numbers". 0 and 1 are two numbers (digits).

- RG>

I am very much familiar with the etymology of "binary", latin btw being a grammatical form of the word bi = 2... but i would like to stand by my opinion, that zero simply doesn't belong in a sudoku, for the simple reason, that it's a game of adding numbers. Should you place a zero in a sudoku-block that block would theoretically still be blanc. Thus a sudoku in binary code would be only 1 block.. a binary sudoku in the etymological understanding to which you refer would hold 1 and 2

It's clearly not a game of adding numbers; there is exactly no adding in it at all (unless you choose some method of solving which uses adding, and we note that a method of solving does not define a problem).

It is a game of symbol logic, or of combinatorics, but definitely not of adding. A 'traditional' sudoku would remain unchanged as a problem if the numbers 1..9 were replaced with the letters a..b or the faces of movie stars. There is no adding inherent to the problem. As such, replacing the numbers 1..9 with 0..8 would be an acceptable formulation of a sudoku problem. Reducing the size of our problem, and so our base number system (from base 9 to base 2) gives us symbols in the range 0..1 - this is perfectly acceptable and is in binary. Yes you could use the symbols 1..2, however the joke is much less funny in that case.

If you object to 0 being used in sudokus for some another reason, be it asthetic otherwise, then that is surely your opinion and I have no objection to you holding it. The objections you have raised, however, are not at all sound. The comic certainly does portray a 'binary sudoku' given any reasonable definition of the two words.

XKCDeviant
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### Re: Binary Sudoku

Is it wrong that I would like to try a Hex Sudoku? Especially as my wife mocks me for how slow I do the normal ones?

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### Re: 0074: "Binary Sudoku"

Resurrecting this again ...

You know, you ended up giving more information than was necessary to solve it. One star?

I think the alt-text says it's "medium" difficulty, for this reason. (also because it makes the joke work better

I'm not sure if I'm misinterpreting the hover text or if he was wrong (seems unlikely) ... but this puzzle is unsolvable. If you interpret it is a one section puzzle, you have duplicates (two zeros and two ones). If you interpret it as four sections, then every section is missing one (it's opposite). Rules of sudoku are are that every section should have every option but no duplicates (and that every row and every column should have every option but no duplicates, but that's not an issue here).

That in addition to the issue of no zeros, but I think that's permissible on humor. The puzzle not being solvable, however, I don't think works with the humor unless that is the *intended* humor.

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### Re: 0074: "Binary Sudoku"

I'm not sure if I'm misinterpreting the hover text or if he was wrong (seems unlikely) ... but this puzzle is unsolvable. If you interpret it is a one section puzzle, you have duplicates (two zeros and two ones). If you interpret it as four sections, then every section is missing one (it's opposite). Rules of sudoku are are that every section should have every option but no duplicates (and that every row and every column should have every option but no duplicates, but that's not an issue here).

Sudoku style puzzles don't have to be restricted to square sections; they work equally well for an m x n grid of n x m sections. For instance, my phone's Sudoku app has a 6x6 grid for its easy level, divided into 2x3 sections.

The puzzle in the comic is clearly a two-section puzzle. The sections can either be the columns or the rows in this instance. The vertical dividing line looks a bit thicker than the horizontal one, so I'd go with the columns as the sections.

Monox D. I-Fly
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### 0074: "Su Doku"

http://www.xkcd.com/74/
Shouldn't there be a 0 in the first row first column and a 1 in the second row one so that each rows' and columns' sums equal 1?
Finally found one comic mentioning a Trading Card Game:
https://xkcd.com/696/

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### Re: 0074: "Su Doku"

(Not sure if you've checked the accepted format for Comic threads starting. I see you've been adding a few recently.)

Although you can work with "numbers sum to <value>", Sudoku isn't even a mathematical thing at heart (unlike Kakuro puzzles, etc). It's just ultimately a symbolic set that can be enumerated, and even taken advantage of in the likes of the Killer Sudoko/Sumdoku extension to the puzzle.

The problem with this puzzle is that it's not obvious whether this is a 2x1-sized major grid of 1x2-sized minor grids, or the inverse. It could be either (and equally solved by your solution), but if it's a single 2x2 minor-grid or a 2x2 grid of minor single-cells then it breaks the general form of the puzzle. The rough drawing hints at, but does not confirm, it being 'true', but is the central disecting vertical line just bold enough to be a major-grid division?

Note that this is "Medium difficulty" probably because it isn't the hardest uniquely-soluble version of the puzzle (that has just one number filled in) nor the easiest soluble version (with three digits entered). Zero fills is non-uniquely soluble, all four fills is the solution!

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### Re: 0074: "Su Doku"

Monox D. I-Fly wrote:
http://www.xkcd.com/74/
Shouldn't there be a 0 in the first row first column and a 1 in the second row one so that each rows' and columns' sums equal 1?

Soupspoon wrote:
(Not sure if you've checked the accepted format for Comic threads starting. I see you've been adding a few recently.)

Yes. Monox, please read the rules before starting threads; I merged one or two into the existing threads, but when I saw just how many threads you started, I boneyarded the rest. Don't start new threads without searching, and use existing threads if you have something to say.
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Monox D. I-Fly
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### Re: 0074: "Su Doku"

Felstaff wrote:Yes. Monox, please read the rules before starting threads; I merged one or two into the existing threads, but when I saw just how many threads you started, I boneyarded the rest. Don't start new threads without searching, and use existing threads if you have something to say.

I did try to search before starting the topics with the keyword exactly as the comics' title. Because there are many results, I used the advanced search function and search within "Topic titles only" but got nothing on some comics. That's why I assumed there hasn't been threads about them yet so I made some. Does the menu "Search within" only give the exact topic title?
Finally found one comic mentioning a Trading Card Game:
https://xkcd.com/696/

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### Re: 0074: "Binary Sudoku"

Again, read the rules... There's even a picture--at the top!--explaining how to list threads numberifically.

I should really add this link in there, too, to make things simpler.
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### Re: 0074: "Binary Sudoku"

The Independent used to have hex sudoku, called super sudoku, on Saturdays. It's 4x4x4x4 rather than 3x3x3x3 and uses 0-9 and A-F rather than 1-9, but it's pretty much exactly the same thing ... just even more tedious.

The i now has idoku, which has a shaded "i" in it that's also a group of 9, sudokarrow, which has twisted lines through it with a circle at one end of each line that must contain the sum of the numbers along it and killersudoku, which has dotted outlines with totals and no repeats.

There's a thread for this stuff, with examples.
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### Re: 0074: "Binary Sudoku"

I once came across some magazine or other with 5*5*5*5 Sudoku (A-Y) among others.I routinely get a magazine that includes a bunch of Sudoku variations (and other pure logic puzzles) - one of my favourites is the Samurai - a regular 3*3*3*3 Sudoku with four variants overlapping the four corner blocks - X-Sudoku (1-9 along each diagonal), irregular regions (rather than 3*3 blocks, other contiguous 9-square regions), extra regions (additional, usually contiguous, 9-square regions overlaid) and one I'm not aware of a snappy name for, where each digit appears in a different place in each 3*3 block.

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### Re: 0074: "Binary Sudoku"

Seeing binary sudoku in a newspaper would be incredibly zen.
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### Re: 0074: "Binary Sudoku"

cjmcjmcjmcjm wrote:Seeing binary sudoku in a newspaper would be incredibly zen.

It would be more so with Unary Sodoku...

Rather than n*m cells in an M*N supergrid with perhaps at least half the subcells having no pre-filled numbers, you'd be left puzzled with the sight of one cell lacking...

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### Re: Binary Sudoku

Zohar wrote:You don't know what you're talking about. Please spare me your quote sniping and general obliviousness.

CorruptUser wrote:Just admit that you were wrong ... and your entire life, cyberspace and meatspace both, would be orders of magnitude more enjoyable for you and others around you.

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### Re: 0074: "Binary Sudoku"

ucim
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### Re: 0074: "Binary Sudoku"

Noting something with amusement is not the same as bitching about it.

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### Re: 0074: "Binary Sudoku"

Everything is bitching.

The internet only has two purposes:
1. Porn
2. Complaining

gd1
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### Re: 0074: "Binary Sudoku"

teelo wrote:Everything is bitching.

The internet only has two purposes:
1. Porn
2. Complaining

Well, it does allow me to play games like Team Fortress 2 and Planetside 2. For TF2, people have the duty in teufort of dancing around while I try to headshot them. In planetside 2 it's similar, except some of them stand still (I like those ones).
There is no emotion more useless in life than hate.

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### Re: 0074: "Binary Sudoku"

Like teelo says: you're supposed to be either teabagging/erotic roleplaying or shouting at the others that you hate them and that they're clearly hacking. Preferably both.

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### Re: 0074: "Binary Sudoku"

Flumble wrote:Like teelo says: you're supposed to be either teabagging/erotic roleplaying or shouting at the others that you hate them and that they're clearly hacking. Preferably both.

Oh, baby, right there. Although you're clearly using a fucking aimbot.