Oracle Scratchpad

June 28, 2011


Filed under: humour — Jonathan Lewis @ 5:50 pm BST Jun 28,2011

There are those who understand the importance of evidence, and those who rely on other kinds of proof.

(You might want to turn your speakers down, or off, before following the link.)


  1. Reminds me of Professor Shelah – who taught logic during my second year at the university.

    He was known for starting to prove a theorem, only to leave the proof unfinished and move on to the next theorem or to interesting results. We never found out if he forgot the end of the proof, or if he got bored or maybe just distracted.

    One day, when he started another proof, only to trail off mumbling “… and from here it is trivial to see the rest…”. One of the students couldn’t take this anymore. He jumped off his chair and said “It doesn’t look trivial! Are you sure its trivial? Please show how its done!”

    Prof. Shelah looked at the proof and thought a bit. After few minutes of deep thought, he dismissed the class for 15 minutes. When we came back from the break he was still in deep contemplation.

    Few minutes later he brightened up, looked at the class, announced: “Yes! It is trivial!” and continued on to the next theorem.

    … You can add this as another method.

    Comment by Chen Shapira — June 28, 2011 @ 8:25 pm BST Jun 28,2011 | Reply

    • Chen,

      Did you ever suffer the “proof by circular reference”, which is a two-step as follows:

      Professor X: “… and Professor Y will be demonstrating the proof of this theorem next term (semester)”.

      Professor Y: “… and Professor X will have demonstrated the proof of this theorem to you last term.”

      Comment by Jonathan Lewis — June 30, 2011 @ 6:19 am BST Jun 30,2011 | Reply

    • Chen,

      This story – albeit about a different professor ( – was part of student folklore at the Department of Mathematics and Informatics (University of Sofia) around 1990… :-)


      Comment by Flado — July 26, 2011 @ 2:01 pm BST Jul 26,2011 | Reply

      • Flado,

        I believe I’ve heard a variation of the same story told about Hardy (the Cambridge mathematician), which resulted in the concept of the “Hardy obvious” (i.e. something that takes a genius 15 minutes to work out that it’s obvious.)

        Comment by Jonathan Lewis — August 1, 2011 @ 11:04 am BST Aug 1,2011 | Reply

  2. 42. | Proof by Douglas Adams |bizarrely improbable coincidence |

    Comment by joel garry — June 28, 2011 @ 11:40 pm BST Jun 28,2011 | Reply

  3. On the topic of evidence and proof, here’s a letter that does a lovely job of explaining the scientific approach to a nine year old.

    Comment by Jonathan Lewis — June 29, 2011 @ 8:27 am BST Jun 29,2011 | Reply

  4. I particularly like #5, which applied to physics might have disuaded Einstein from bringing down Newton’s theory.

    And speaking of time and space, I also like #8, where if we move from time to space we have Fermat’s Last Theorem, and elegant proof of which won’t fit in this margin.

    Comment by Mark W. Farnham — June 29, 2011 @ 10:20 am BST Jun 29,2011 | Reply

  5. Number #36 is my favorite and it works all the times indeed!

    Number #8 was my math professor’s favorite.

    Number #3 is used extensively and it works just great until the contrary is proved by someone else ;-)


    Comment by Flavio C. — July 2, 2011 @ 4:26 pm BST Jul 2,2011 | Reply

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