The Sphinx's Lair

12:53 AM

0

Sliding-block chess puzzles have gone a little cold, so here be a hearty warm-up! ;D In the below position that I created, it Black to move, but there is a twist: the stipulation is that it is a series-mover-helpmate. You may not know what that is, so here's a brief summary. A series-mover i...

Sphinx

1:32 AM

0

Q: Heyacrazy: Crosses

This is a Heyacrazy puzzle. Heyacrazy is an original genre, inspired by the "two border" rule of Heyawake and Heyawacky. Rules of Heyacrazy: Shade some cells of the grid. Shaded cells cannot be orthogonally adjacent; unshaded cells must be orthogonally connected. There cannot be a li...

logical-deduction grid-deduction

Alconja

2:04 AM

@Sphinx @Deusovi - perhaps I'm being dense, but I don't understand rule 3 at all... Are the black lines "line segments" or "borders"?

Deusovi

The black lines are "borders". The rule is the same as Heyawake, but now "lines" can go in any direction.

Hold on, let me edit in an example

Deusovi

2:17 AM

@Alconja Example added, and changed the phrasing of the third rule - is it clear now?

Alconja

Ahh, you're drawing the line segments...

I believe I get it now. Thanks.

Alconja

4:18 AM

I assume with Heya* puzzles, I'm not allowed to use logic that says "if Configuration X, then there's a square that could ambiguously be either filled or not, therefore not Configuration X"...

Omega Krypton

i gave up after 10 mins lol

Alconja

I did a little when deus clarified rules, but then had to actually do work... coming back for another brief look.

Omega Krypton

I'm burying myself in making a long story for an upcoming puzzle

Deusovi

@Alconja yeah, in grid-deduction puzzles, logic that relies on the fact that a puzzle has a unique solution is generally discouraged

Alconja

That's what I figured. Definitely fails the "does it feel like cheating?" test.

msh210

5:06 AM

@Deusovi My impression is it's perfectly acceptable in sudoku.

Not sure what I base that impression on, tbh. (And I'm extremely unfamiliar with heya*, so can't speak to them.)

Deusovi

What, really? I've heard the opposite.

Though I don't do much sudoku - not a fan of the genre.

msh210

You want to take this outside?

Huh?

Do you?

'Cause I'm ready.

oh, wait, Poe's law...... let me clarify, that was a joke

Deusovi

don't worry, I got that one

Anyway, the reasons for uniqueless logic being bad in general are:

(1) You can't be sure that your solution is the only solution. (What if there's a mistake in the puzzle?)

and (2) Because the creator couldn't use uniqueness logic, there must be some other logical path built in. If you make deductions based on the puzzle having a unique solution, you skip (/ miss out on) that logical path, which is less fun for both the creator and the solver.

(I would feel no shame using uniqueness logic on a puzzle I knew to be computer-generated. And I probably wouldn't mind using it for Sudoku either, but that's because all Sudoku puzzles "feel" computer-generated to me.)

msh210

I'm not sure (2) is correct. Specifically, I recall reading/hearing that there are sudoku puzzles that are designed specifically to be solvable only by use of such steps. I may, however, be misremembering.

Why do you say the creator can't require uniqueness logic?

Deusovi

5:23 AM

Because they have to know that the solution is unique? If the creator used uniqueless logic themselves while making the puzzle, then they're relying on a fact that may not be true about the puzzle they eventually make.

msh210

Hm... I've never tried to create a sudoku puzzle at all, but I imagine that that should be doable.

Deusovi

Here's an example with Slitherlink, which I think is easier to see. (Rules of Slitherlink: Draw horizontal and vertical lines between some of the given dots to form a single loop. Numbers tell how many segments of their square are part of the loop.)

puzz.link/p?slither/3/3/dg77d

msh210

(should be doable = not my creating a sudoku puzzle. I mean: someone's creating it with the requirement that the solver rely on uniqueness)

@Deusovi ok, I've found a solution to that one rot13(ybbxf yvxr n ovt ryy), so assuming uniqueness I'm done. You're saying that's insufficient?

Deusovi

Yes, I am -- because this puzzle isn't unique.

msh210

ah, fair enough. :-) I didn't read the rules carefully enough, and assumed uniqueness. But for sudoku, I think standard rules include uniqueness, no?

Deusovi

5:28 AM

There's a 2 in the bottom left. That 2 can be satisfied either using both the bottom and left edges, or the top and right edges. (These are the only options; any other configurations of edges around that loop would leave and endpoint stranded in the corner.) By uniqueness, it must be the bottom-left configuration, since if it were the top-right configuration it could just be flipped to the bottom left. This configuration must be forced by the central 2, then, and that gives the loop.

Of course, the problem there is that the answer isn't unique. If you assume the answer is unique, then you only get a single answer. But if I was constructing this puzzle, I couldn't make that assumption, because I would be misled into thinking it was unique.

msh210

right, you can't assume the answer is unique when making the puzzle... but that doesn't mean you can't guarantee an answer that's {unique under the assumption that the answer is unique}

Deusovi

So the constructor has to use some other logic when verifying uniqueness. And that logic should be accessible to the solver too.

Alconja

(they could use brute force to prove uniqueness, but then presumably there'd be some other way of proof too, even if by guess contradiction)

msh210

Let's suppose Slitherlink rules included "Answers are unique.".

Deusovi

(yeah, brute force is a method they could use, but any puzzle requiring that kind of brute force is bad)

msh210

5:33 AM

Then the one you linked to above would still be valid, because you could use that uniqueness to solve it.

All I'm saying is that the same is true for sudoku. (Dunno why I feel like capitalizing Slitherlink but not sudoku. Weird.)

Deusovi

No, it wouldn't be valid - it would break one of the rules of the genre. Just like a Sudoku puzzle with two 8s in the same row in the givens would be invalid, even if it happened to produce a valid answer ignoring that.

msh210

Which rule of the genre? Don't forget this is with the rule that I added.

Deusovi

Yes, it would break the rule you added.

Because the answer wouldn't be unique.

msh210

The solver must construct an answer that solves the rules of the puzzle (now including uniqueness). He can use the fact that the loop must be continuous to construct it, can't he? He can use the fact that each number must be bordered by that many segments, to construct the loop. So why can't he use uniqueness to construct the loop? It's just another rule like continuity and the number rule.

(Again, assuming we've added a uniqueness rule.)

Deusovi

The solver can do that -- there's no law of physics preventing it, nor will police come to arrest you. But it's "unclean", in a sense - it's not the same thing as just using one of the other rules. The other rules constrain how you draw lines, or place numbers, or shade cells, or whatever. The statement "this puzzle has a unique solution" doesn't: it says nothing about the solution, but instead tells you something about the set of possible solutions.

msh210

5:45 AM

True, fair enough; nonetheless, as I mentioned, I recall reading that some sudoku puzzles require to you to use that rule, so... unclear though it feels (to you) you may have to do it (if you ever do sudoku).

Deusovi

Well, you don't have to - you can always brute-force. But a puzzle that pushes the solver to use uniqueness logic is poorly-designed, because it relies on an extra assertion given with the individual puzzle (sometimes implicitly, sometimes explicitly) rather than solely on the rules of the genre itself.

I'm sure there are Sudoku puzzles where that is the intended route to the solution. And those are bad puzzles. Using the assertion that a puzzle has a unique solution is like solving a problem on a multiple-choice test by figuring out that the answer must be even, and then circling the only even number out of the four options.

You haven't really solved the problem if you do that (even if you have technically found the correct answer), and if the problem was designed to be solved that way then it's poorly-made.

(Of course, that may be a good strategy on that type of exam, where the goal is (unfortunately) to get the right answer quickly rather than to completely understand every problem backwards and forwards. But it shouldn't be satisfying to do that.)

msh210

CCCC hint 3: The answer is unique.

;-)

Omega Krypton

thanks. that helps.

msh210

(At least, I hope it is.)

Omega Krypton

well, if it is really useful, you would have pinned it. so obviously, it is not ;-)

msh210

6:00 AM

:-)

Sphinx

9:23 AM

1

Q: What is an Independent Word™?

This is in the spirit of the What is a Word/Phrase™ series started by JLee with a special brand of Phrase™ and Word™ puzzles. If a word conforms to a special rule, I call it an Independent Word™. Use the following examples below to find the rule. $$ % set Title text. (spaces around the text A...

pattern word-property

Sphinx

11:01 AM

2

Q: A song from a play

I went to a play recently. Immediately after the intermission, some cast members sang this short (and terribly written) song: This treatise we sing on this section of stage is not so long as to discourage. It'll draw all your effort out, lessen your boredom: you'll be like a farm machin...

poetry

Sphinx

11:40 AM

0

Q: map 5 unequal ranges to id

This is actually coming from a business place, but it's all about being able to do math tricks, and that's why I'm posting here. I want to implement the following function: f(x)= 1, x ∈ (-∞,0] 2, x ∈ (0,1500] 3, x ∈ (1500,5000] 4, x ∈ (5000,10000] 5, x ∈ (10000,+∞) The problem is I am...

mathematics computer-puzzle

Sphinx

12:00 PM

2

Q: Three Singles in Three Clubs

These three belong to three different clubs. First one, very popular, is singles only club. It is closed for new membership. Second one, very useful, is for singles and couples. It is open for new members but very hard to get in now. Unlike the first two, the third Club is diff...

riddle

Alconja

12:14 PM

@msh210 Wouldn't have even come close without the clues and Gareth's ramblings, but the (presumably unique) solution is: MIX TAPES - def: Some homemade presents; cocktail => MIX; 7- => SEPT-, up => T_PES; + a hint of A(bsinthe)

Gareth McCaughan

aha!

msh210

12:40 PM

@Alconja Thank you!

You're getting there. Note that the "answer" need not be a word. — msh210 2 mins ago

^ Is the puzzle too confusing like this? I mean, will a typical solver assume he's looking for a single word? He's not.

Is there some tag I should use to dispel that assumption?

Alconja

CCCC: Drone of returned spirit echoed (6)

jafe

don't think there is

of course you can always add a sentence in the description like "the answer is a scottish musical instrument"

Alconja

^

jafe

but i don't think it's correct to assume you need a single word if nothing is specified

Alconja

Probably not correct to assume, but also not surprising that people would.

Sphinx

12:59 PM

0

Q: Ambitious Puzzler's Masyu

Contrary to the lazy puzzler, the creator of this masyu is too ambitious that he adds not only one but two extra stones, so the puzzle is unsolvable. Finish his job for him by removing those additional stones on the board so that the result is a uniquely solvable masyu. Normal masyu rules apply....

grid-deduction masyu

msh210

@Alconja mur+mur

<

@jafe okay, then. Thanks.

Alconja

@msh210 Yep. Back to you. :)

msh210

Hopefully this one will be quicker...

CCCC: From the Isle of Man?? Reportedly, they're from Manchester (5)

jafe

MANCS (~manx)

@msh210 oops, forgot to ping so here it is ^

msh210

1:37 PM

@jafe Yep!

jafe

CCCC: Cover the cost of soda outside New York university (4, 2)

msh210

2:23 PM

@jafe po(ny u)p

darn... maintenance

@msh210 correct!

@msh210 next one pls

1

Q: Which household object drew this pattern?

In my home is a common household object. I securely attached a marking pen to some point on the household object, and I placed a sheet of graph paper next to the pen, so the paper would not move. I then operated the household object in the normal manner, and it drew the pattern below. What is the...

pattern visual situation

msh210

2:50 PM

CCCC: Inside of goal-line edifice is the air that I breathe? (3,1,4)

Omega Krypton

3.14...

Omega Krypton

3:03 PM

hey, do anagrams in cryptic clues form the whole word?

like can we do america = *ame +rica

@jafe

Deusovi

that's completely fine, though it's generally more difficult (so you should keep the rest of the wordplay simple)

Omega Krypton

ok thanks

Sphinx

1

Q: Heyacrazy: Forks

This is a Heyacrazy puzzle. Rules of Heyacrazy: Shade some cells of the grid. Shaded cells cannot be orthogonally adjacent; unshaded cells must be orthogonally connected. When the puzzle is solved, you may not be able to draw a line segment that passes through two borders, and does no...

logical-deduction grid-deduction

Deusovi

^ puzzle 2 of... 11 or so? There's no meta with these, just a sequence of logic puzzles that should get harder over time (plus some variants stuffed at the end)

Omega Krypton

nice

Sphinx

3:36 PM

0

Q: A mini cryptic cube

A quick teaser, enjoy! Across 3 Dance bores serious (5) 6 Light angry look (5) 11 Finally asked it to agree (5) 12 Rails - cunning homes of thieves (5) 15 Trap saner design (5) 16 Kingdom with real messy leader (5) Down 1 Earth would heartlessly bear resistance (5) 2 Fruit left precious sto...

cryptic-crosswords three-dimensional

Gareth McCaughan

4:34 PM

@msh210 Solution to your CCCC is ALL I NEED (substring indicated by "Inside of").

msh210

5:14 PM

@GarethMcCaughan Yes, indeed. And the reference (for those who didn't catch it) is to the lyrics of the song "The Air that I Breathe".

Sphinx

7:12 PM

2

Q: What brought these couples together?

Sometimes it's difficult for outsiders to understand what brings a couple together. What brings each of these couples together? ENTER INPUT ROTOR MOVES TIGER STATS TARGET DENIER LITER SAVER CIGAR STAMP STOPS RECAP DETER CIDER NORSE SITED SENILE MARTS STUNS ...

wordplay pattern

Sphinx

7:32 PM

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Q: Bankers with rancor

Three colleagues at the bank are boasting to each other… Colleague 1: “Ask anybody – I’m clearly the best.” Colleague 2: “And how do you figure that?!” Colleague 1: “Well, just mention my name and people instantly think of one thing: ‘quality’ – I’m practically synonymous with i...

knowledge wordplay story

Sphinx

8:31 PM

1

Q: Heyacrazy: "LMI"

This is a Heyacrazy puzzle, originally constructed for a test for Logic Masters India. Rules of Heyacrazy: Shade some cells of the grid. Shaded cells cannot be orthogonally adjacent; unshaded cells must be orthogonally connected. When the puzzle is solved, you must not be able to draw...

logical-deduction grid-deduction

Sphinx

9:10 PM

0

Q: What is the relationship between the following numbers?

Specify the clue in this pattern: 22 12 0 15 18 15 27 26 18 13 8 22 27 13 0

riddle number-sequence arithmetic

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