## Search found 2068 matches

- Tue Jul 24, 2018 6:40 am UTC
- Forum: Logic Puzzles
- Topic: Tower of Hanoi Variant
- Replies:
**2** - Views:
**402**

### Re: Tower of Hanoi Variant

There's a very detailed book "The Tower of Hanoi - Myths and Maths" from 2013 which has a whole chapter devoted to this. The four-peg version is also called Reve's Puzzle, given that name by H.E. Dudeney who was the first to write about this generalization in his 1908 Canterbury Puzzles. T...

- Thu Jun 21, 2018 3:55 pm UTC
- Forum: Mathematics
- Topic: Repetitive Coin Flip Probability
- Replies:
**16** - Views:
**1875**

### Re: Repetitive Coin Flip Probability

Seems like that kind of bias would have to be in the method of flipping rather than the coin itself. Quite so. Here's a demonstration of tossing a coin ten times in a row, getting heads each time. (For full disclosure: that is me, and it took me only about 7 or 8 takes. Sorry, I couldn't resist pos...

- Wed May 30, 2018 9:46 am UTC
- Forum: Science
- Topic: How much is 1e340 j of energy?
- Replies:
**19** - Views:
**1589**

### Re: How much is 1e340 j of energy?

What I was thinking is that there are some very large numbers that are useful, or at least used, in various types of mathematical explorations, ponderings or theories, perhaps used in things like cryptography (eg: very large primes) or other esoteric fields, even if its just exploring the nature of...

- Thu Feb 01, 2018 6:48 am UTC
- Forum: Logic Puzzles
- Topic: Rubrics Cube of Doom
- Replies:
**3** - Views:
**2168**

### Re: Rubrics Cube of Doom

I plan on painting over the squares of a rubrics cube It's called a Rubik's Cube, named after its inventor Ernö Rubik. Such maze cubes have been designed before. The standard maze cube design was made by Christoph Lohe, and he explains the reasoning behind it here: The Maze Cube You can buy sticker...

- Tue Jan 02, 2018 7:32 am UTC
- Forum: Language/Linguistics
- Topic: Is this logical statement true or false?
- Replies:
**9** - Views:
**3049**

### Re: Is this logical statement true or false?

[...] or that it does have meaning, and it is simply false, since there are no colorless green ideas, and therefore there can't be any sleeping, furiously or otherwise. In mathematical logic such a statement would be considered true. Non-existent objects have any property you can name because to pr...

- Fri Nov 24, 2017 9:55 am UTC
- Forum: Fictional Science
- Topic: How do you define..."you"?: Question about Infinite Universe
- Replies:
**22** - Views:
**3440**

### Re: How do you define..."you"?: Question about Infinite Universe

andykhang wrote:The alternate self idea? That's there is infinite version of you when you have infinite universe?

Are you talking about a multiverse (i.e. parallel universes) rather than a single infinitely large universe?

- Tue Nov 21, 2017 7:11 pm UTC
- Forum: Mathematics
- Topic: periodicity in LCGs
- Replies:
**2** - Views:
**1916**

### Re: periodicity in LCGs

You have X_{t+1} = (aX_t + c) mod 2^k You can simply look at it mod 2^1: X_{t+1} = (aX_t + c) mod 2 The resulting lowest bit of X_{t+1} does not depend on any of the higher bits of X_t, only on the lowest bit. Therefore, this reduced PRNG essentially has an internal state consists only of a single b...

- Fri Nov 17, 2017 11:12 am UTC
- Forum: Mathematics
- Topic: Maximizing 2 Variables
- Replies:
**19** - Views:
**3518**

### Re: Maximizing 2 Variables

Eebster the Great wrote:Again, you are maximizing the objective function, not "two variables". You can certainly maximize a function of multiple variables (if it has a maximum).

I'm not disagreeing, just explaining why you need such a function and giving a simple example.

- Fri Nov 17, 2017 9:50 am UTC
- Forum: Mathematics
- Topic: Assassin Problem over the Internet
- Replies:
**40** - Views:
**6380**

### Re: Assassin Problem over the Internet

Hmm, watching the videos, I don't like the solutions presented. The originating person's proposal is, with the extraneous stuff removed: 1. Number all the people 1-8. 2. Get cards numbered 1-8, in order. Cycle the deck (move top card to bottom) a random number of times. 3. Give the first ca...

- Fri Nov 17, 2017 9:16 am UTC
- Forum: Mathematics
- Topic: Maximizing 2 Variables
- Replies:
**19** - Views:
**3518**

### Re: Maximizing 2 Variables

Yeah, with x(t) and y(t) plotted on an x-y plane, maximizing x and y at the same time means having a cusp that "points" toward the top-right. cusp.png Such a cusp is not a general feature of parametric plots, and it's irrelevant (to the general case) that if your graph is just a line segm...

- Thu Sep 07, 2017 1:13 pm UTC
- Forum: News & Articles
- Topic: Bedfordshire Professor Claims Voynich Breakthrough
- Replies:
**9** - Views:
**8457**

### Re: Bedfordshire Professor Claims Voynich Breakthrough

**BUMP**

Another reasonably convincing interpretation:

https://www.the-tls.co.uk/articles/publ ... -solution/

Another reasonably convincing interpretation:

https://www.the-tls.co.uk/articles/publ ... -solution/

- Wed Sep 06, 2017 5:55 am UTC
- Forum: Logic Puzzles
- Topic: 538 hats riddle
- Replies:
**20** - Views:
**4331**

### Re: 538 hats riddle

With 7 people you can use two rules. Rule one - If you see four people with the same color, then you must guess that you have the opposite color. Win - 70/128 Lose - 42/128 Rule two - If you see six people with the same color, then you must guess that you have the opposite color Win - 14/128 Lose -...

- Mon Sep 04, 2017 3:14 pm UTC
- Forum: Logic Puzzles
- Topic: 538 hats riddle
- Replies:
**20** - Views:
**4331**

### Re: 538 hats riddle

It is not stated clearly in the question, but I assume that each hat's colour is chosen independently, 50:50 either colour. What you say is true if you make a fixed choice beforehand about who is going make a guess. However, you don't have to do that. For example, consider the smaller version of the...

- Sat Sep 02, 2017 1:59 pm UTC
- Forum: Language/Linguistics
- Topic: Miscellaneous language questions
- Replies:
**559** - Views:
**78685**

### Re: Miscellaneous language questions

Maybe at some point the y spelling had dots added because as I wrote before the letter y is not used much normally. In cursive handwriting the ij is essentially identical to y apart from the dots, and it is very hard to resist the urge to automatically add them. That is really interesting. Is this ...

- Sat Sep 02, 2017 11:53 am UTC
- Forum: Language/Linguistics
- Topic: Miscellaneous language questions
- Replies:
**559** - Views:
**78685**

### Re: Miscellaneous language questions

Non-English 26ers include Dutch (Ij directly replacing Y, it seems, a detail to which I would clearly defer to any Dutch forumite who cared to comment) I'm Dutch, so let me wade in here about the Dutch "IJ". It represents a vowel sound, one of the many diphthongs spoken Dutch has. It is n...

- Fri Sep 01, 2017 2:27 pm UTC
- Forum: Mathematics
- Topic: Possible "Spot it!"-like decks
- Replies:
**30** - Views:
**6853**

### Re: Possible "Spot it!"-like decks

See I thought that when you made cards like these it was what he was asking about. I thought these worked, Meets all his conditions. 1376524 1745632 1234567 1472635 1563472 1625743 All your cards have the same symbols. We don't care about their order on each card, so every pair of cards in your set...

- Thu Aug 31, 2017 9:40 am UTC
- Forum: Language/Linguistics
- Topic: Miscellaneous language questions
- Replies:
**559** - Views:
**78685**

### Re: Miscellaneous language questions

Non-English 26ers include Dutch (Ij directly replacing Y, it seems, a detail to which I would clearly defer to any Dutch forumite who cared to comment) I'm Dutch, so let me wade in here about the Dutch "IJ". It represents a vowel sound, one of the many diphthongs spoken Dutch has. It is n...

- Wed Jul 26, 2017 12:06 pm UTC
- Forum: Mathematics
- Topic: Determining line of sight over time
- Replies:
**30** - Views:
**5615**

### Re: Determining line of sight over time

By the way, having the observers moving instead of stationary does not change the difficulty of this question. Are you dropping the implicit assumption that the objects in the space are stationary? I guess so, because I never really thought of the objects as stationary. *since the line end points r...

- Wed Jul 26, 2017 5:21 am UTC
- Forum: Mathematics
- Topic: Determining line of sight over time
- Replies:
**30** - Views:
**5615**

### Re: Determining line of sight over time

Sure. I'm trying to understand the point? Do you think her/his problem is solvable? The OP is not clear: If both points are stationary is it trivial to determine whether or not they can see each other. However, both points are moving. As you said, and I agree, that part is still essentially trivial...

- Tue Jul 25, 2017 2:40 pm UTC
- Forum: Mathematics
- Topic: Determining line of sight over time
- Replies:
**30** - Views:
**5615**

### Re: Determining line of sight over time

There are two points in a space. The space is filled with objects. If both points are stationary is it trivial to determine whether or not they can see each other. However, both points are moving. Luckily, they are moving in straight lines with a constant speed. How would I go about determining at ...

- Mon Jul 24, 2017 11:57 am UTC
- Forum: Logic Puzzles
- Topic: Arithmetic puzzle
- Replies:
**5** - Views:
**4168**

### Re: Arithmetic puzzle

It is not possible.

For n>1 we have:

log n! < log n

So n! always has fewer than n

For n>1 we have:

log n! < log n

^{n}= n log n < n^{2}So n! always has fewer than n

^{2}digits (except for 1! and 0!).- Fri Jul 21, 2017 12:28 pm UTC
- Forum: Logic Puzzles
- Topic: Isosceles triangles and circles : puzzle connection
- Replies:
**15** - Views:
**3563**

### Re: Isosceles triangles and circles : puzzle connection

Read what was written in the picture : "At right you have samples of isosceles triangles connecting three circles" Is there any precision about right triangle or not? no. So triangles could be right or not. Just watch carefully my examples : you have right triangles and not right triangle...

- Sun Jul 16, 2017 5:27 pm UTC
- Forum: Movies and TV Shows
- Topic: Doctor Whom
- Replies:
**4917** - Views:
**652043**

- Fri Jul 07, 2017 7:52 am UTC
- Forum: Language/Linguistics
- Topic: How to write in plain language
- Replies:
**32** - Views:
**5644**

### Re: How to write in plain language

Are you getting that 20 words/sentence average from your personal digital copy? I admit that is an awful lot. On the other hand, by Shane Snow's calculations , Hemingway's books have an overall Flesch-Kincaid reading level of 4, and reading ease of a startling 95. So clearly it matters which metric...

- Sun Jul 02, 2017 1:24 pm UTC
- Forum: Language/Linguistics
- Topic: Regional Dialect and Idiolect Oddities (pronunciation)
- Replies:
**941** - Views:
**230698**

### Re: Regional Dialect and Idiolect Oddities (pronunciation)

Question: Here in the US decimal numbers are written with a "decimal point " as e.g. 3.14, which is said out loud as "three point one four". I know that in some (many?) other countries decimals are written using a comma as 3,14. In this case how is the number said out loud? Is i...

- Sat May 27, 2017 5:29 am UTC
- Forum: Language/Linguistics
- Topic: “good big”
- Replies:
**7** - Views:
**3375**

### Re: “good big”

See also this language log post. It mentions some examples where the most common word order defies categorization, e.g. "ugly little"/"big ugly".

- Tue May 02, 2017 2:57 pm UTC
- Forum: Mathematics
- Topic: Halting Problem
- Replies:
**208** - Views:
**29759**

### Re: Halting Problem

This what I don't understand - my assumption (perhaps mistaken) is that the Oracle program must have the last move (i.e., it must say that whatever's been fed to it will halt or that what's been fed to it will loop forever). Is that assumption incorrect? That is correct. If you had a perfect Oracle...

- Thu Apr 27, 2017 7:22 am UTC
- Forum: Coding
- Topic: Coding: Fleeting Thoughts
- Replies:
**9853** - Views:
**1749617**

### Re: Coding: Fleeting Thoughts

Microsoft Powerpoint is Turing complete:

https://www.youtube.com/watch?v=uNjxe8ShM-8

https://www.youtube.com/watch?v=uNjxe8ShM-8

- Wed Apr 12, 2017 12:24 pm UTC
- Forum: Logic Puzzles
- Topic: Two secrets
- Replies:
**20** - Views:
**7446**

### Re: Two secrets

I think I have an O(log(N)) solution. Let A initially be {1, 2, 3, ..., N-1}. At all times, we know that at least one of the numbers is in A. Divide A into three roughly equal sets A 1 , A 2 , and A 3 , and ask about A 1 ∪ A 2 , A 1 ∪ A 3 , and A 2 ∪ A 3 . If we get a "yes" response to on...

- Mon Apr 10, 2017 2:11 pm UTC
- Forum: Science
- Topic: Does the geographical distribution of the northern and southern hemispheres affect the rotation of the Earth?
- Replies:
**8** - Views:
**2490**

### Re: Does the geographical distribution of the northern and southern hemispheres affect the rotation of the Earth?

Is the biggest effect to do with moving closer/further from the poles, thereby moving mass closer/further from the axis, and changing the moment of inertia?

- Thu Mar 30, 2017 9:23 am UTC
- Forum: Mathematics
- Topic: Futurama Puzzle Game
- Replies:
**5** - Views:
**2761**

### Re: Futurama Puzzle Game

That is an interesting question. Of course, in the episode the problem was fixed by adding two people who hadn't swapped yet, which adds enough available swaps to always make it solvable. It looks like there's some parity rule that forces complete paths to have an even number of steps, but I'm not s...

- Mon Mar 06, 2017 12:42 pm UTC
- Forum: Science
- Topic: How can we experminetly determine the acceleration due to gravity?
- Replies:
**20** - Views:
**4495**

### Re: How can we experminetly determine the acceleration due to gravity?

But for an object rolling without slipping, some of the gravitational potential energy is transformed into rotational energy. If I do the calculations right, the proportion depends on the ratio of the moment of inertia of the object and the product of its mass and the square of its rolling radius, ...

- Thu Mar 02, 2017 9:35 am UTC
- Forum: Logic Puzzles
- Topic: Escape the Frictionless Circle
- Replies:
**156** - Views:
**46822**

### Re: Escape the Frictionless Circle

LaserGuy wrote:If you fall outward,

That's a big if. How do you fall outward if your feet slide inward?

- Thu Feb 02, 2017 3:26 pm UTC
- Forum: Science
- Topic: Coincidence in Tycho's Model of the Solar System
- Replies:
**6** - Views:
**2632**

### Re: Coincidence in Tycho's Model of the Solar System

The model in that video is not to scale. The gaps between the orbits of neighbouring planets in that video are all the same, whereas in actuality the distances increase further out. Because the video uses equal distances, you will get such apparent coincidences as it makes sixth planet exactly twice...

- Wed Feb 01, 2017 4:22 pm UTC
- Forum: Science
- Topic: Newton's shell theorem with negative mass
- Replies:
**12** - Views:
**3170**

### Re: Newton's shell theorem with negative mass

I actually did my doctoral dissertation on negative mass, but mostly on cosmological scales. A matched pair of positive and negative mass particles would indeed accelerate forever. This doesn't violate conservation of energy, since the negative mass has negative kinetic energy. Generalizing, a gas ...

- Mon Jan 30, 2017 1:23 pm UTC
- Forum: Science
- Topic: Explosions and Unobtainium, as pertains to video game physics
- Replies:
**9** - Views:
**2866**

### Re: Explosions and Unobtainium, as pertains to video game physics

Here's another data point. The Mythbusters tested a scene from Lethal Weapon 2: https://en.wikipedia.org/wiki/MythBusters_(2011_season)#Episode_178_.E2.80.93_.22Toilet_Bomb.22 It turns out that that a rather heavy metal bathtub can protect you from a blast that would otherwise have been lethal (180 ...

- Wed Jan 11, 2017 4:44 pm UTC
- Forum: Movies and TV Shows
- Topic: Star Wars Episode VIII naming contest
- Replies:
**35** - Views:
**7295**

### Re: Star Wars Episode VIII naming contest

Just for larfs... What is your guess about what Episode VIII will be called? I'll lay down The Ways Of The Force I think they'll want to give a three-act structure to the new trilogy, so the middle film needs to be a slightly darker one where the Empire New Order strikes back. The title will probab...

- Tue Dec 13, 2016 4:44 pm UTC
- Forum: Logic Puzzles
- Topic: Word Puzzle.
- Replies:
**6** - Views:
**4402**

### Re: Word Puzzle.

I don't think so. A quick google for "reversible words" led me to this page . I then filtered out all the ones that are not 3 letters long, and removed eel/lee due to the repeated letter. The remaining words are almost all consonant/vowel/consonant, except for: are/era ate/eta bro/orb So i...

- Sun Dec 04, 2016 12:49 pm UTC
- Forum: Language/Linguistics
- Topic: Simple Writer poetry for the Holiday Season
- Replies:
**11** - Views:
**5775**

### Re: Simple Writer poetry for the Holiday Season

If I interpret your post correctly, you don't know the mechanism of how Simple Writer works in its way of changing certain input words into red fronts. I should be grateful, if some other readers of this thread could help me to learn that mechanism. The xkcd simplewriter page seems to use the javas...

- Wed Nov 16, 2016 7:01 am UTC
- Forum: Science
- Topic: V=IR - bad science or am I being thick?
- Replies:
**15** - Views:
**4357**

### Re: V=IR - bad science or am I being thick?

The further you go to the top-left, the more reactive the elements are. Clarification: metals in the lower left are more reactive than those in the upper left. Lithium in water will fizz around enthusiastically; sodium will ignite, and it gets more exciting from potassium on down. (Francium is too ...