Page 2 of 2 FirstFirst 12
Results 16 to 24 of 24

Math Help - Cardinalities and ultimate sets

  1. #16
    Member
    Joined
    Sep 2011
    Posts
    114

    Re: Cardinalities and ultimate sets

    The prof says there is no typo.

    I am going to go down to his office tomorrow. I will be sure to let you know what is going on here.
    Last edited by ehpoc; November 29th 2011 at 05:38 PM.
    Follow Math Help Forum on Facebook and Google+

  2. #17
    Member
    Joined
    Aug 2011
    Posts
    127

    Re: Cardinalities and ultimate sets

    Thanks, let us know. Something's definitely fishy...

    Oh, and while you're at it, ask him what a positive set and an ultimate set are, since I still have no clue what those mean. (And where did he get those terms...?)
    Follow Math Help Forum on Facebook and Google+

  3. #18
    Member
    Joined
    Sep 2011
    Posts
    114

    Re: Cardinalities and ultimate sets

    Well first off ultimate sets are all of the possible combinations of all intersections of the sets. I am sure that doesn't make sense.

    But say you have set A and set B and A intersects B.

    The ultimate sets would be the intersections

    AB^c

    A^cB

    A^cB^c

    AB

    Basically it is all of the smallest possibly sets, or all the sets that have no subsets in them.

    so for three sets A B C it would be the intersections....


    A^cBC
    AB^cC
    ABC^c
    A^cB^cC
    A^cBC^c
    AB^cC^c
    A^cB^cC^c
    ABC

    So anyways on to this question. Which in all honesty was just a HORRIBLE question, and one could argue the epitome of what a trick question is. The prof actually went over it quickly at the beginning of class because "lots of people were confused by it". Ya no doubt genius it is completely horrible and a trick question.

    3. In a sample of 1000 cottage owners, 570 owned their cottages with no mortgage and
    also owned cars; 340 owned mortgaged cottages, owned cars, and had electricity; 189
    had neither mortgages nor cars nor electricity; 760 owned cars. Find the cardinalities of
    the ultimate sets.
    Well guess what? The data is invalid, and he intended it to be. You are supposed to use ultimate sets to make the determination that the data is invalid.....yet it gives NO implication that this is what you are supposed to do.

    You would think he would word the question as "use ultimate sets to determine if the data is valid or not"

    So anyways you are simply supposed to that The information given is invalid.
    Follow Math Help Forum on Facebook and Google+

  4. #19
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,610
    Thanks
    1576
    Awards
    1

    Re: Cardinalities and ultimate sets

    Quote Originally Posted by ehpoc View Post
    The ultimate sets would be the intersections
    AB^c
    A^cB
    A^cB^c
    AB

    so for three sets A B C it would be the intersections....
    A^cBC
    AB^cC
    ABC^c
    A^cB^cC
    A^cBC^c
    AB^cC^c
    A^cB^cC^c
    ABC
    What a very odd name for this concept.
    I feel for you with this particular instructor. As an ex-dept-chair I know what needs to be done here. If I were you, I would discuss this with your department leader or the Dean of your division.
    Attached Thumbnails Attached Thumbnails Cardinalities and ultimate sets-untitled.gif  
    Last edited by Plato; November 30th 2011 at 03:50 PM.
    Follow Math Help Forum on Facebook and Google+

  5. #20
    Member
    Joined
    Sep 2011
    Posts
    114

    Re: Cardinalities and ultimate sets

    And say what?
    Follow Math Help Forum on Facebook and Google+

  6. #21
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,610
    Thanks
    1576
    Awards
    1

    Re: Cardinalities and ultimate sets

    Quote Originally Posted by ehpoc View Post
    And say what?
    "Why are we being given material so far out of the main stream, the generally accepted, definitions in the area of general set theory". Some stellar professors such as R L Moore can be given a pass on this. But generally I would expect instructors to adhere to standard definitions.
    Follow Math Help Forum on Facebook and Google+

  7. #22
    jar
    jar is offline
    Newbie
    Joined
    Nov 2011
    Posts
    4

    Re: Cardinalities and ultimate sets

    Quote Originally Posted by Annatala View Post
    Thanks, let us know. Something's definitely fishy...

    Oh, and while you're at it, ask him what a positive set and an ultimate set are, since I still have no clue what those mean. (And where did he get those terms...?)
    See the below link for positive set.
    http://www.mathhelpforum.com/math-he...tml#post698677

    Ultimate set is the intersection of all n sets, each is either one of A, B, C,.... or its complement.

    These are the definitions given to us in class.

    I am hoping he will going to curve the final grade......
    Follow Math Help Forum on Facebook and Google+

  8. #23
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,610
    Thanks
    1576
    Awards
    1

    Re: Cardinalities and ultimate sets

    Quote Originally Posted by jar View Post
    I am hoping he will going to curve the final grade.
    I would hope he would be dismissed for gross ignorance.
    Follow Math Help Forum on Facebook and Google+

  9. #24
    Member
    Joined
    Aug 2011
    Posts
    127

    Re: Cardinalities and ultimate sets

    So...here's what I'm gathering from this, parsed into language I can understand:

    "Ultimate set" = set
    "Positive set" = any set, except for two: U, and U \ (union of all other named sets).
    Instructor = stupid, stupid, stupid
    Follow Math Help Forum on Facebook and Google+

Page 2 of 2 FirstFirst 12

Similar Math Help Forum Discussions

  1. What are Positive Sets, Ultimate Sets?
    Posted in the Discrete Math Forum
    Replies: 8
    Last Post: November 29th 2011, 04:11 PM
  2. Sets with cardinalities
    Posted in the Discrete Math Forum
    Replies: 1
    Last Post: July 27th 2010, 06:43 PM
  3. select-and-ultimate mortality table
    Posted in the Business Math Forum
    Replies: 0
    Last Post: September 29th 2009, 07:53 PM
  4. Proof: cardinalities of sets
    Posted in the Discrete Math Forum
    Replies: 1
    Last Post: February 26th 2009, 09:23 PM
  5. Cardinalities of sets
    Posted in the Discrete Math Forum
    Replies: 0
    Last Post: October 16th 2008, 03:35 AM

Search Tags


/mathhelpforum @mathhelpforum