## Search found 54 matches

Fri Oct 24, 2014 4:46 pm UTC
Forum: Logic Puzzles
Topic: Two guards, two doors, no instructions
Replies: 63
Views: 16119

### Re: Two guards, two doors, no instructions

I think I am just echoing Qaanol's point here: Xenomortis: what is to stop the untruthful guard saying: "If you ask me the set up, I'd say "chose any door, both lead to freedom." Of course, if you did ask that guard, they'd give you a completely different answer, so they have ...
Thu Oct 23, 2014 10:20 am UTC
Forum: Logic Puzzles
Topic: Two guards, two doors, no instructions
Replies: 63
Views: 16119

### Two guards, two doors, no instructions

The basic set up is familiar: Two guards guard two doors. One door leads to freedom, one door leads to death. You can ask one question. One guard always lies, one always tells the truth. But you know none of that....Perhaps the sign explaining it has been stolen. Before you ask your question, the gu...
Mon Sep 29, 2014 8:09 am UTC
Forum: Logic Puzzles
Topic: Simple grid placement puzzle
Replies: 12
Views: 3345

### Re: Simple grid placement puzzle

Nice analysis!

I think we have a winner.
Sat Sep 27, 2014 9:55 am UTC
Forum: Logic Puzzles
Topic: Simple grid placement puzzle
Replies: 12
Views: 3345

### Re: Simple grid placement puzzle

That looks good, lunch meat . I think we followed similar logic paths to get there: 2 has to go on a middle edge (not corner), so we can start with: ? 2 ? ? ? ? ? ? ? ? ? ? ? ? ? ? (in your case, you started with the bottom row. Same difference). If we are aiming for the lowest solut...
Thu Sep 25, 2014 8:51 am UTC
Forum: Logic Puzzles
Topic: Simple grid placement puzzle
Replies: 12
Views: 3345

### Re: Simple grid placement puzzle

That didn't last long! curiosityspoon and nitrodon have both pretty much replicated the analysis I made to solve the puzzle, so I won't bother publishing that. Now 4x4 with the same rules is a bit tougher to find a solution - there are quite a few. Can you find one of them? How about the lowest solu...
Wed Sep 24, 2014 4:33 pm UTC
Forum: Logic Puzzles
Topic: Simple grid placement puzzle
Replies: 12
Views: 3345

### Simple grid placement puzzle

The challenge: Place the digits 1 through 9 into a 3x3 grid subject to two constraints: 1. No numbers that exactly divide each other can be in the same row, column, or long diagonal (1 doesn't count as a divisor for this puzzle) 2. No numbers that are +/-1 of each other can be adjacent vertically o...
Thu May 09, 2013 1:30 pm UTC
Forum: Logic Puzzles
Topic: Team challenge
Replies: 22
Views: 8374

### Re: Team challenge

It can't be done, except in the degenerate case where sets of three people have (by random choice) all picked each other. In that case, A, B, and C can be equidistant from each other, independently of D, E and F being a different equidistance, and so on. But four people cannot be equidistant from ea...
Mon Feb 11, 2013 10:48 am UTC
Forum: Logic Puzzles
Topic: Tea or Coffee
Replies: 13
Views: 6182

### Re: Tea or Coffee

The answer above works for a perfect spoon - i.e. one that is completely dry at the end of each transfer. A real spoon will be wet, thus abstracting a small quantity of the fluid(s) at the end of the two transfers. We need to know the amount and proportions of the two fluids in each of the three loc...
Fri Feb 01, 2013 12:39 pm UTC
Forum: Logic Puzzles
Topic: Pennies in Boxes
Replies: 85
Views: 50738

### Re: Pennies in Boxes

Sell the boxes intact for USD5 each. Offer a prize of USD1000 for anyone who has purchased two that are identical. (You'll need to put some sort of buyer-id mark on them to stop box buyers swapping boxes between themselves after purchase). If your initial sample result (that no boxes two seem alike)...
Fri Feb 01, 2013 12:20 pm UTC
Forum: Logic Puzzles
Topic: The truthteller and the politician
Replies: 65
Views: 25664

### Re: The truthteller and the politician

Spoiler:
Do you want people to vote for you at the next election?

A truthteller would simply say no. A politician could say no, but they'd be committing career suicide, so they'd be left waffling in the wind.

Alternatively:
Spoiler:
Do you do a good job in representing your constituents?
Sun Sep 09, 2012 11:05 am UTC
Forum: Logic Puzzles
Topic: Pennies in Boxes
Replies: 85
Views: 50738

### Re: Pennies in Boxes

One word: Crowdscourcing. Get other people do do the work for you, and have them pay you do it it. Rent access to the box at (say) USD5 per hour. Let the extractors take whatever cardboard and pennies they can extract. Sell them knives, coffee, charge for bathroom access, charge high rates f...
Tue Mar 13, 2012 7:19 pm UTC
Forum: Logic Puzzles
Topic: Problem with Carpooling
Replies: 26
Views: 10328

### Re: Problem with Carpooling

Some further issues regarding car pool fairness. 1. With an irregular group of carpoolers (as stated in the original spec) there may be days where more than a carful want a ride. There'd be two (or more) drivers that day. 2. The workload for a driver is (loosely) correlated with the number of riders...
Fri Nov 25, 2011 6:32 pm UTC
Forum: Logic Puzzles
Topic: Help crack the code plzz ......
Replies: 2
Views: 1726

### Re: Help crack the code plzz ......

Looks like a SHA1 digest.

If so all you have to do to win is
Spoiler:
guess the word or phrase Ted has encoded. It probably includes the string TalkMagic.
Tue Nov 22, 2011 2:35 pm UTC
Forum: Logic Puzzles
Topic: 2 + 2 = 5
Replies: 175
Views: 53821

### Re: 2 + 2 = 5

But what if there are holes in the number line, and the first hole turns out (on closer inspection) to be where we've always assumed 4 to be? This is explored in Rudy Rucker 's short story, 2 + 2 = 5 http://kasmana.people.cofc.edu/MATHFICT/mfview.php?callnumber=mf589 (Even if it unlikely that 4 is l...
Tue Oct 18, 2011 5:29 pm UTC
Forum: Logic Puzzles
Topic: Algebra Crypotgram Puzzle
Replies: 13
Views: 4622

### Re: Algebra Crypotgram Puzzle

Wow -- that old programmer's joke has catalyzed a lot of multi-base alphameric research. Thanks for sharing the findings.

Here's a simple looking alphametic equation that has unique solution in every base from 5 to, well, there may be no limit -- try it for yourself:

Code: Select all

`JUL + 4 = USA `
Fri Oct 14, 2011 11:22 am UTC
Forum: Logic Puzzles
Topic: Algebra Crypotgram Puzzle
Replies: 13
Views: 4622

### Re: Algebra Crypotgram Puzzle

Thanks for playing, solving, and confirming my suspicions about the uniqueness of the answers. Incidentally, there are three solutions in hexadecimal (base 16), and one of them is noticeably bad. You'll know what I mean if you find that solution (in the base-16 variant, C,D,E are still variables, no...
Sun Oct 09, 2011 1:10 pm UTC
Forum: Logic Puzzles
Topic: Algebra Crypotgram Puzzle
Replies: 13
Views: 4622

### Re: Algebra Crypotgram Puzzle

feel free to post if you find more puzzles of this type Okay, here's one. It's based on the old joke: why do computer programmers confuse Halloween with Xmas? DEC * 25 = OCT * 31 Where, as usual, letters are difference digits, and D and O are never zero (no leading zeroes). Digits are themselves. *...
Thu Sep 29, 2011 9:41 pm UTC
Forum: Logic Puzzles
Topic: Solve this! (A mathemagical game.)
Replies: 62
Views: 10355

### Re: Solve this! (A mathemagical game.)

Fair cake algorithm -- this works for a round cake with precisely vertical cuts -- it would not work if one person's idea of fairness was for them to have all the cream filling via some horizontal cuts. The solution is shown for three people, but it extends to higher numbers. First, make one arbitra...
Fri Sep 23, 2011 2:28 pm UTC
Forum: Logic Puzzles
Topic: A Syllogism by Lewis Carroll
Replies: 11
Views: 5397

### Re: A Syllogism by Lewis Carroll

What seems to be missing is a qualification: All meat that I eat for dinner is meat that I buy at the market. All meat that I buy at the market was raw meat at the time of purchase Therefore: All meat that I eat for dinner was raw meat at the time of purchase Consider an equivalent syllogism: All pe...
Wed Sep 14, 2011 3:12 pm UTC
Forum: Logic Puzzles
Topic: Interesting Math/Logic Puzzle
Replies: 4
Views: 2156

### Re: Interesting Math/Logic Puzzle

I wrote a very short REBOL script:
Spoiler:

Code: Select all

`start: 1-August-1948loop 10 [print start: start - 1000]5-Nov-19459-Feb-194315-May-194019-Aug-193723-Nov-193427-Feb-19322-Jun-19296-Sep-192611-Dec-192316-Mar-1921`
Wed Sep 14, 2011 3:56 am UTC
Forum: Logic Puzzles
Topic: Interesting Math/Logic Puzzle
Replies: 4
Views: 2156

### Re: Interesting Math/Logic Puzzle

Spoiler:
1926
Fri Sep 09, 2011 1:35 pm UTC
Forum: Logic Puzzles
Topic: Chess problem I just invented; can't solve
Replies: 11
Views: 3783

### Re: Chess problem I just invented; can't solve

This can be done,sort of, in a match of two or more games white starts a new game 1. Nf3 Nf6 2. Ng1 Ng8 3. Nf3 Nf6 4. Ng1 Ng8 = draw by repetition It is now the original Black player's turn to move to start the next game. Admittedly, they'll move with the White pieces, but they were Black so...
Mon Aug 01, 2011 8:43 am UTC
Forum: Logic Puzzles
Topic: An alien in need
Replies: 6
Views: 2763

### Re: An alien in need

Eternal Questionner wrote:Left to right's 50:50 anyway

Not quite - you are overlooking Boustrophedon writing.
Tue Jun 28, 2011 3:11 pm UTC
Forum: Logic Puzzles
Topic: Numbers and Squares
Replies: 16
Views: 4276

### Re: Numbers and Squares

Here's an answer that squeezes the facts until they fit, and produces the same end result as GeorgeH. Add all corner numbers that are either prime or one less than a prime. The in-box number is that total expressed in base 17 8 + 4 + 9 + 2 ===> 4 + 2 = 6 2 + 17 + 6 + 10 ===> 2 + 17 + 6 + 10 = 35 ...
Fri Jun 03, 2011 12:14 pm UTC
Forum: Logic Puzzles
Topic: Longest english contraction
Replies: 21
Views: 44009

### Re: Longest english contraction

How is this scored? Most apostrophes wins, with letter count as a tiebreaker?

Good question!

That sounds a fine scheme.
Fri Jun 03, 2011 9:47 am UTC
Forum: Logic Puzzles
Topic: Longest english contraction
Replies: 21
Views: 44009

### Longest english contraction

Someone asked this on the Stack Exchange English site, and it got closed as unsuitable for a language site. Perhaps it'll fare better in a logic puzzle forum. The puzzle is (as expressed by the original poster) to find the: largest word with multiple contractions . Their offering is .... The fish...
Sat May 14, 2011 10:19 am UTC
Forum: Logic Puzzles
Topic: Twins in a Maze
Replies: 81
Views: 20854

### Re: Twins in a Maze

If we're on a featureless sphere orbiting a featureless star, then I'd fly to the L2 Lagrange point -- as would my twin robot; after we've used our unlimited time to develop space flight...If I can see the sky, then it's part of the maze by the original definition, that that's a logi...
Wed May 11, 2011 1:26 pm UTC
Forum: Logic Puzzles
Topic: Twins in a Maze
Replies: 81
Views: 20854

### Re: Twins in a Maze

I don't want to hijack this thread into a discussion on logical puzzles vs engineering puzzles … so please feel free to cut out this post and its context and park somewhere else. But many logic puzzles are also engineering puzzles. Consider, for example, the whole genre of coin piles that have to be...
Wed May 11, 2011 7:02 am UTC
Forum: Logic Puzzles
Topic: Twins in a Maze
Replies: 81
Views: 20854

### Re: Twins in a Maze

But there is always going to be a symmetry breaker -- if not in the twins themselves (their names or ages as previously discussed) then in their initial position or orientation in the maze. Developing that spoiler further -- consider the example given of a perfectly circular maze and the twins dropp...
Mon Mar 07, 2011 12:24 pm UTC
Forum: Logic Puzzles
Topic: Not friends on the earth
Replies: 19
Views: 3853

### Re: Not friends on the earth

So then I guess a better way would be saying "Distribute N points on a sphere surface..." rather than having them all start at the north pole Puzzles are often characterized by being expressed in a narrative form, and wrapped in a story. Some can be re-cast into a formal mathematical form...
Sun Mar 06, 2011 8:57 pm UTC
Forum: Logic Puzzles
Topic: Not friends on the earth
Replies: 19
Views: 3853

### Re: Not friends on the earth

My unstated assumptions in the original question were for
• final distance
• as measured on the surface (ie no tunnelling with tape measures)
So we're looking for final great circle distances.
Thu Feb 24, 2011 10:17 am UTC
Forum: Logic Puzzles
Topic: Not friends on the earth
Replies: 19
Views: 3853

### Re: Not friends on the earth

Ralp.....The 2, 3, 4 solutions may not be very interesting, but I do not think there are any solutions for 5 and above. The original puzzle asks for the distances to be maximal and equal . Your suggested 5 solution has four people around the equator. They are not all the same distance from each othe...
Wed Feb 23, 2011 11:18 pm UTC
Forum: Logic Puzzles
Topic: Not friends on the earth
Replies: 19
Views: 3853

### Re: Not friends on the earth

To clarify a possible misreading: everyone stays on the surface of the earth at all times.
Wed Feb 23, 2011 10:27 pm UTC
Forum: Logic Puzzles
Topic: Not friends on the earth
Replies: 19
Views: 3853

### Not friends on the earth

For the purpose of these puzzles, the Earth is a uniform, smooth, sphere of circumference 40,000km. Easy to start: a. Two people who dislike each other very much stand at the North Pole. One moves to be as far away from the other person as they can. How far is that? Now, the real problems: b. Three...
Wed Feb 23, 2011 12:09 pm UTC
Forum: Logic Puzzles
Topic: Sum of consecutive integers
Replies: 10
Views: 4354

### Re: Sum of consecutive integers

Thanks for the corrections.

My script emitted the right solutions, but injuries sustained during the edit wars still affect my ability to cut'n'paste properly.

Incidentally, if we permit negative integers, then even powers of 2 have a solution:
Spoiler:
-3 + -2 + -1 + 0 + 1 + 2 + 3 + 4 = 4
Wed Feb 23, 2011 10:10 am UTC
Forum: Logic Puzzles
Topic: Sum of consecutive integers
Replies: 10
Views: 4354

### Re: Sum of consecutive integers

(belated reply to skyreaper....other edits and replies have outdated this while I was typing) You are on the right track with the idea you added in an edit. Incidentally, 6177 has five solutions: 2058 + 2059 + 2060 = 6177 1027 + 1028 + 1029 + 1030 + 1031 + 1032 = 6177 199 + 200 + 201 + 202 + 203 + 2...
Wed Feb 23, 2011 9:31 am UTC
Forum: Logic Puzzles
Topic: Sum of consecutive integers
Replies: 10
Views: 4354

### Re: Sum of consecutive integers

That was quick!

Your suspicion is well-founded. If you can deduce the algorithm for producing the consecutive integers for a given number, you'd be able to tell if
• there are any other unreachable numbers
Wed Feb 23, 2011 8:59 am UTC
Forum: Logic Puzzles
Topic: Sum of consecutive integers
Replies: 10
Views: 4354

### Sum of consecutive integers

Some numbers can be expressed as the sum of consecutive positive integers: 2 + 3 = 5 1 + 2 + 3 + 4 = 10 Some can be expressed in more than one way: 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 = 72 23 + 24 + 25 = 72 Can you find all the ways to express these integers -- or explain why it is not possible? 99...
Thu Feb 17, 2011 9:41 pm UTC
Forum: Logic Puzzles
Topic: Twins in a Maze
Replies: 81
Views: 20854

### Re: Twins in a Maze

The problem states: You and your twin know that, being identical in mind and body, each will arrive at the same method as the other Therefore we will both arrive at the same method, X . For us to succeed we must break the symmetry, and have one of us implement it as X while the other implements it a...
Sun Feb 06, 2011 7:16 pm UTC
Forum: Logic Puzzles
Topic: Twins in a Maze
Replies: 81
Views: 20854

### Re: Twins in a Maze

The original rules state that: You cannot call out to one another, leave markings or a trail. So shouting is ruled out. But it is physically impossible, given the problem states that the twins are human, (the problem is posed for You and your identical twin ) not to leave a trail. Again, the problem...