Which Sequences are Graphical? (Degree Sequences and Havel-Hakimi algorithm) | Graph Theory

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  • Опубликовано: 2 окт 2024

Комментарии • 72

  • @WrathofMath
    @WrathofMath  Месяц назад +1

    Support the production of this course by joining Wrath of Math as a Channel Member for exclusive and early videos, original music, and upcoming lecture notes for the graph theory series! Plus your comments will be highlighted for me so it is more likely I'll answer your questions!
    ruclips.net/channel/UCyEKvaxi8mt9FMc62MHcliwjoin
    Graph Theory course: ruclips.net/p/PLztBpqftvzxXBhbYxoaZJmnZF6AUQr1mH
    Graph Theory exercises: ruclips.net/p/PLztBpqftvzxXtYASoshtU3yEKqEmo1o1L

  • @Alex-fh4my
    @Alex-fh4my 5 месяцев назад +5

    Thank you so much. My lecturer does not show any examples and just states theorems and proofs over and over again with no intuition behind these things. If only my tuition money could be going to people like you instead.

  • @tjllinas9102
    @tjllinas9102 3 года назад +3

    these videos are more informative than the class im paying thousands of dollars to take lol. I appreciate them a lot man, keep it up!!

    • @WrathofMath
      @WrathofMath  3 года назад +4

      I'm glad they've been helpful, thanks a lot for watching and let me know if you ever have any questions! Many more videos to come, and be sure to check out my Graph Theory playlist if you haven't already: ruclips.net/p/PLztBpqftvzxXBhbYxoaZJmnZF6AUQr1mH

    • @tcritt
      @tcritt 3 года назад +1

      Same here, man. I was sent a load of pdfs at the start of the course and I'm expected to just read it all and assimilate it. Thank f**k for RUclips and creators like this guy!

    • @PunmasterSTP
      @PunmasterSTP 4 месяца назад

      How'd the rest of your class go?

  • @ItEngineer1998
    @ItEngineer1998 3 года назад +6

    Capgemini brought me here 😂😂

    • @anupr7925
      @anupr7925 4 месяца назад

      And Cognizant brought me here 😂

    • @LearningCS-jp4cb
      @LearningCS-jp4cb 2 месяца назад

      @@anupr7925 Can i know for what reason? Are you guys preparing to appear for their aptitude exam or are these videos recommended for skill upgrade?

  • @PunmasterSTP
    @PunmasterSTP 4 месяца назад

    Havel-Hakimi? More like "Thanks for these lectures; yes indeed-y!" 🙏

  • @nikhilmeena7258
    @nikhilmeena7258 Год назад +3

    great setup, everything is decorated so well, that it is feeling soothing while watching the video

    • @WrathofMath
      @WrathofMath  Год назад

      Thank you, that's exactly what I wanted to achieve with the Christmas videos! I wasn't able to do them last year simply because of time constraints, but if I can ever work on these full time, the Christmas set ups will be INTENSE.

  • @flyinghigh3433
    @flyinghigh3433 6 месяцев назад +1

    Thank you❤

  • @juanroa9304
    @juanroa9304 Год назад

    Thank you so much for this! you saved my life!!!

  • @achuthas2875
    @achuthas2875 Месяц назад

    So does “graphical” mean connected or disconnected graph? Also thank you for the precise explanation 🔥

  • @abhinandanbarua8677
    @abhinandanbarua8677 6 месяцев назад

    The last sequence has odd number odd ones. How is it graphical?

  • @zhuoyangzhang4821
    @zhuoyangzhang4821 Год назад +1

    OMG THIS IS WAY TOO HELPFUL TY VERY MUCHHH

  • @7lool125
    @7lool125 2 месяца назад

    s3 could have 7 if there are loops? Am i wrong

  • @navpreetkaur5005
    @navpreetkaur5005 4 месяца назад

    While drawing the graph can't we draw the loops to show that it is graphical ....please explain as I have my exam coming

  • @rikupt8092
    @rikupt8092 3 года назад +4

    Great video, helped me a lot! I just have one question:
    If we have a multigraph then the 3 3 1 1 sequence would be possible since we could have the vertices with degree 3 connect to each other and each of them with 1 vertice of degree 1 and then just add a loop to the vertices of degree 3 making it possible?

    • @marylynnhayek3807
      @marylynnhayek3807 Год назад

      So you want to connect the vertices of degree 3 with the vertices of degree 1, then connect the vertices of degree 3 with each other, and finally create a loop on the vertices of degree 3? i think the sequence would be : [5 5 1 1],

    • @marylynnhayek3807
      @marylynnhayek3807 Год назад

      But if you only create a loop on the vertices of degree 3, all while connecting 1 vertex of degree 3 to a vertex of degree 1, i think it would then work. the sequence would stay the same. no need to connect the vertices of degree 3 with each other, since a loop is counted twice in a degree.

    • @mariap.9768
      @mariap.9768 Год назад

      if loops and disconnected graphs are allowed, for a non directed graph:
      edges: (v1, v2),(v3, v4),(v3,v3),(v4,v4)
      d1 = d2 = 1,
      d3 = d4 = 2 + 1 = 3
      sequence 3,3,1,1
      However the algorithm used in the video is only for simple graphs.

    • @Wonderland_247
      @Wonderland_247 Год назад

      Agreed! Surely in graph theory you could have one vertex with multiple loops coming off it. Then then number of edges will be greater then the number of vertices.

  • @sziluv
    @sziluv 3 года назад +1

    thank you so much, you always help me.😊❤️

    • @WrathofMath
      @WrathofMath  3 года назад

      You're very welcome, so glad I can help! Thanks for watching! 😀

  • @navpreetkaur5005
    @navpreetkaur5005 4 месяца назад +1

    While drawing the graph can't we draw loops to show that it is graphical...please explain as I have my exam coming

    • @navpreetkaur5005
      @navpreetkaur5005 4 месяца назад

      Also pls tell that is {2,3,4,4,5} graphical is some multigraph possible to draw with this degree sequence

  • @Alex-ln5vb
    @Alex-ln5vb Год назад

    Great great great! Thank you soooo much for the help

  • @kartikeyasaraswat2736
    @kartikeyasaraswat2736 3 года назад +5

    I'm a data science student and learning graph theory. I was having trouble understanding the concepts, thank god! that I found this channel. Sean, you're an amazing teacher, explanations are damn!.... I would really appreciate it if you could make some videos on the application of graph theory like stable allocation, pair matching, etc. Also, it'd be great to have some videos on topology and applications.

  • @teo_d_david
    @teo_d_david 3 года назад +2

    took me like half an hour to understanbd it throught my uni book which didnt explain it at all and 5 minutes from your video. Keep it up! Thanks a lot!

    • @WrathofMath
      @WrathofMath  3 года назад +1

      So glad it helped! Thanks for watching and if you're looking for more graph theory, check out my playlist! ruclips.net/p/PLztBpqftvzxXBhbYxoaZJmnZF6AUQr1mH

    • @teo_d_david
      @teo_d_david 3 года назад

      @@WrathofMath Wow! Thanks. I have a sequence a=d1, d2... dn and one b=n-d1-1,..., n-dn-1, how can i prove this "prove a is graphical (iff) if only b is graphical". There are no numbers..

  • @ruscul7155
    @ruscul7155 Год назад +2

    this is the best video that ive been looking for.. thanks alot. just subbed

    • @WrathofMath
      @WrathofMath  Год назад

      Glad to help, thanks for your support!

  • @minwoogwak99
    @minwoogwak99 11 дней назад

    Only 12 minutes of video saved my few hours for preparing exam

    • @WrathofMath
      @WrathofMath  10 дней назад

      Glad to help, thanks for watching!

  • @xxtuddlexx
    @xxtuddlexx 9 месяцев назад

    oh baby the santa of math to save my fucking C in discrete 2 thank fuck your coloring video was clutch

    • @WrathofMath
      @WrathofMath  9 месяцев назад

      Hell yeah - good luck my man!

  • @ManuPela
    @ManuPela 10 месяцев назад

    but does a lace not allow the sequence 3 3 1 1 to be done, with a lace on each of the 3s and by joining them you get to degree 3. And the other two 1 degress you just connect them to each other?

  • @KihemboScovia
    @KihemboScovia 5 месяцев назад

    Describe the conditions of the graph being graphical

  • @samsunnahar9175
    @samsunnahar9175 23 дня назад

    Thanks a lot for excellent video!!

    • @WrathofMath
      @WrathofMath  23 дня назад

      Glad to help, thanks for watching!

  • @Sachinguptahbs
    @Sachinguptahbs Год назад

    1:26

  • @abie4830
    @abie4830 Год назад +1

    this channel should have atleast 500k subscribers

  • @luciano8158
    @luciano8158 Год назад

    awesome

  • @aditichavan3427
    @aditichavan3427 2 года назад +1

    Very Precise Information Given...Great 😃👍👍

  • @gouravrout5769
    @gouravrout5769 2 года назад

    thank u sir.....nice explanation ....INDIA

  • @abenezeralemayehu5596
    @abenezeralemayehu5596 9 месяцев назад

    i just love u u make my life easier

  • @terriblegamer2050
    @terriblegamer2050 5 месяцев назад

    Very helpful video. 🎉

    • @WrathofMath
      @WrathofMath  5 месяцев назад

      Glad it was helpful! Thanks for watching!

  • @haoruwen4105
    @haoruwen4105 2 года назад

    Great video. thank you so much

  • @tcritt
    @tcritt 3 года назад

    @Wrath of Math - I came back for some last-minute revision. You should put "Havel-Hakimi" in the title. It will make it easier for people to find and you'll get the views it deserves.

    • @WrathofMath
      @WrathofMath  3 года назад

      Thanks for the idea, you're right! I think I wasn't familiar with Havel-Hakimi name when I made this!

  • @devjyoti5614
    @devjyoti5614 Год назад

    What about (3 2 1 0)

    • @WrathofMath
      @WrathofMath  Год назад +1

      Not graphical, consider the fact that the first vertex needs to be adjacent to all the others, which is impossible because of the 0.

  • @bytecode5834
    @bytecode5834 11 месяцев назад

    Red is a bit distracting but the class is very good. Thanks for the video :)

    • @WrathofMath
      @WrathofMath  11 месяцев назад

      Thank you for watching!

  • @xxxxx409
    @xxxxx409 Год назад

    thanks for the help!

  • @wishmanoor-fo7rp
    @wishmanoor-fo7rp 10 месяцев назад

    Thank you so much for such an informative video

  • @aditishelke6775
    @aditishelke6775 3 года назад

    just in time for my test tomorrow.. thank you so much!!!
    Loving the christmas outfit :)

    • @WrathofMath
      @WrathofMath  3 года назад +3

      You're very welcome! Good luck on the test and thank you - I'm enjoying the season, it'll be a bummer to go back to normal videos after the end of December, but I think people will be ready for it haha!

  • @joshyoo4041
    @joshyoo4041 3 года назад

    Thank you for the video! is the theorem you used the Havel-Hakimi?

    • @WrathofMath
      @WrathofMath  3 года назад

      My pleasure, thanks for watching! And I am not sure if the theorem is due to Havel and Hakimi, or if they just published algorithms using the theorem.

  • @austinclark3439
    @austinclark3439 3 года назад +1

    great video. In my discrete math class, I am told that using the Havel-Hakimi algorithm is helpful to determine if a degree sequence is graphical, like S5, but I am told that to constructively prove it's graphical, I still need to draw a graph with such a degree sequence.
    I am looking for helpful guide to drawing graphs from a degree sequence, knowing it is graphical. Advice? That'd be helpful. Start with the vertex of greatest degree, then draw them adjacent to the lesser degree vertices?

  • @tcritt
    @tcritt 3 года назад

    This was great. Thanks!

    • @WrathofMath
      @WrathofMath  3 года назад +1

      No problem, thanks for watching! If you're looking for more on graph theory, check out my playlist if you haven't yet: ruclips.net/p/PLztBpqftvzxXBhbYxoaZJmnZF6AUQr1mH

    • @tcritt
      @tcritt 3 года назад

      @@WrathofMath Bookmarked!