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Thread: Two Logic problems that I am stuck on

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    Default Two Logic problems that I am stuck on

    So I have been staring at this for a while now and can't figure out where to start.

    1. Let g be a function from set A to B, and f be a function from B to C. Prove or Disprove the following statement

    f of g is bijective iff f is bijective and g is bijective.



    2. Place as small an upper bound as you can on the number of turns required to solve the white cross on Rubik's cube. Justify your answer.



    Don't need a walkthrough, just a place to start.

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    I have no idea how to approach number 2, but I have found some quantitative sources on the "God's Number." Its a little over my head right now, but you can take a look:

    http://www.cube20.org/
    http://www.cubezone.be/crossstudy.html

    I hope it helps

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    Quote Originally Posted by yourule97 View Post
    I have no idea how to approach number 2, but I have found some quantitative sources on the "God's Number." Its a little over my head right now, but you can take a look:

    http://www.cube20.org/
    http://www.cubezone.be/crossstudy.html

    I hope it helps
    I don't know either lol, Googleing found that it is 8 but I can't prove it.

    Any idea on 1?

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    Quote Originally Posted by JPHamlett View Post
    So I have been staring at this for a while now and can't figure out where to start.

    1. Let g be a function from set A to B, and f be a function from B to C. Prove or Disprove the following statement

    f of g is bijective iff f is bijective and g is bijective.



    2. Place as small an upper bound as you can on the number of turns required to solve the white cross on Rubik's cube. Justify your answer.



    Don't need a walkthrough, just a place to start.
    Not sure if i correctly understand first one.The part about from set a to b. If set is defined as a part of a function for example from x=5 to x=15. Then any alternating function like sinus for example would make f of g NOT bijective as it would have 2 intersection points within the line on a x axis plane.

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    Quote Originally Posted by yourule97 View Post
    I have no idea how to approach number 2, but I have found some quantitative sources on the "God's Number." Its a little over my head right now, but you can take a look:

    http://www.cube20.org/
    http://www.cubezone.be/crossstudy.html

    I hope it helps
    A little off topic but the 1st link is about God's Algorithm which is the maximum number of turns (HTM) required to solve the Rubik's Cube from any state. I believe however the 2nd link contains what OP needs (fixed color cross solving which is white in the case of OP)

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    Hate maths, sorry i cant help you.

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    Quote Originally Posted by IvanMartinez View Post
    Hate maths, sorry i cant help you.
    Stop with your spam please. Look at the date of the thread. Try to avoid grave digging.
    I am Ggzz..
    Hackintosher

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    Quote Originally Posted by Brandon View Post
    Stop with your spam please. Look at the date of the thread. Try to avoid grave digging.
    Well since this hasn't been solved should I put the solution just in case others might want to see it?
    I can't find any recent math help post and I want to contribute to the community. I have a degree in math and study computer science so I would love to help in any way that I can.

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    Quote Originally Posted by hunterofagoodtime View Post
    Well since this hasn't been solved should I put the solution just in case others might want to see it?
    I can't find any recent math help post and I want to contribute to the community. I have a degree in math and study computer science so I would love to help in any way that I can.

    Go ahead and post one more one liner on any thread with a reply older than a few months.. I get that you need 10 posts to message people. But you're not posting anything useful. This is known as grave-digging and spamming and spambots don't last too long.


    "Since this hasn't been solved should I put the solution"..
    Your answer was: "Hate maths, sorry i cant help you."

    You have been warned.. Actually twice now.

    I'm not a mean person, but that was your second post and still no solution other than you hate math and a post asking if you should post the solution. Your next post/thread should be quite useful..


    You have 10 of these:
    Last edited by Brandon; 03-06-2018 at 09:34 PM.
    I am Ggzz..
    Hackintosher

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    Quote Originally Posted by Brandon View Post
    Go ahead and post one more one liner on any thread with a reply older than a few months.. I get that you need 10 posts to message people. But you're not posting anything useful. This is known as grave-digging and spamming and spambots don't last too long.


    "Since this hasn't been solved should I put the solution"..
    Your answer was: "Hate maths, sorry i cant help you."

    You have been warned.. Actually twice now.

    I'm not a mean person, but that was your second post and still no solution other than you hate math and a post asking if you should post the solution. Your next post/thread should be quite useful..


    You have 10 of these:
    wtf I never said I hate math - why would I get a degree in math if I hated it?????? - and I am posting useful stuff here, and it's not to do personal messages it's because I want to contribute. I posted a solution to proving the growth of functions using asymptotic notation, how is that not useful??? It was an old post but come on there are no recent math post and that one hadn't been solved yet - neither has this one. All I was asking is if it is okay to solve older math post that hadn't been solved yet just in case others wanted to see the solution. I also posted a research paper I wrote on RS botting in the writing and blogging section. I don't know why you came at me like that it was quite insulting.
    Last edited by hunterofagoodtime; 03-08-2018 at 06:52 PM.

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