Sunday, February 13, 2011

Set A Q.17

K4 and Q3 are graphs with the following structures.

K4 is a square with four vertices every vertex connecting to every other vertex
Q3 is a graph representing a cube.

A) K4 is planar while Q3 is not         B) Both K4 and Q3 are planar
C) Q3 is planar while K4 is not         D) Neither K4 nor Q3 is planar

My answer is
B) Both K4 and Q3 are planar.
The cube can also be untangled to form a planar graph.
Post your comments here

18 comments:

  1. yeah this is d right one...
    its given on:
    http://www.math.lsa.umich.edu/mmss/coursesONLINE/graph/graph5/

    ReplyDelete
  2. I got B) Both K4 and Q3 are planar
    but in the key it is given as A)K4 is planar while Q3 is not.
    What are your comments??

    ReplyDelete
  3. yeah both r planer....
    given on:
    http://www.math.lsa.umich.edu/mmss/coursesONLINE/graph/graph5/

    ReplyDelete
  4. Q3 represents a cube i.e. all the sides should be equal. But representing the cube as given on the above website is actually transforming a 3D figure to 2D figure.

    Your explanation will be correct, if we are considering a cuboidal figure.

    But, the definition of Q3 in Graph theory, it represents a proper cube & k4 is a well connected graph having four vertices. We doesn't consider about the length in case of k4 but you have to take length into consideration while talking about Q3.

    I recommend you to go through Hamilton's circuit once again.

    I hope your doubts are now clear, why they have publish such an answer. Isn't it?

    Another point, you may be correct, just wait for the GATE result, everything will become clear about this question.

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  5. Confirmed ... Both are planar ... No doubts

    If K4 is planar .. as in K4 everyone would be transforming one diagonal into curved line coming from outside ... so if you can change that line to curve .. you can change size of sides of cube .. and its not mentioned anywhere that it is cube .. it is just looking like one ..

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  6. @ Prateek,
    It is not mentioned in the question paper that Q3 is cube but you should refer to a good book (A foriegn author) about the definition of k4 & Q3.
    Read again about the definition, I had written above.

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  7. Please reply to me at
    http://gateanswers.blogspot.com/2011/02/gate-2011-discussion.html?showComment=1297702247937#c1080850676935059820

    What is the expected cutoff this year for CS??
    what is your score??

    ReplyDelete
  8. Please help me to type the GATE 2011 question paper by typing some questions here. So that i'll copy them and make a full document without any watermarks and easy to read for all the students.
    Thanks.

    ReplyDelete
  9. yeah answers of most of questions given in gate forum are wrong
    please visit this site to find trusted solutions
    www.gatesolutions.weebly.com

    ReplyDelete
  10. @asd:Are the answers given in this blog not right.
    Discuss

    ReplyDelete
  11. both Q3 and K4 are 3d
    if we consider them planar then:
    2 edges intersect in both
    but this cant happen as edges can meet only at vertex
    so both are 3d
    2d view is given

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  12. Both are planar.
    Read the below page and see the examples given on the right.
    http://en.wikipedia.org/wiki/Planar_graph

    What i mean is we can draw the graphs by adjusting the edges so that no two edges intersect.

    ReplyDelete
  13. Both are planar.
    Read the below page and see the examples given on the right.
    http://en.wikipedia.org/wiki/Planar_graph

    What i mean is we can draw the graphs by adjusting the edges so that no two edges intersect.

    ReplyDelete