Math humor

      Phyllis Diller (1917-20120), outspoken and funny, pioneering female comedian, died Monday, August 20.  Her self-deprecating humor was hugely hilarious -- and it helped the rest of us also not to take ourselves too seriously.

     In honor of Phyllis Diller and humor, I first offer a link to a "poem" from a favorite math-cartoonist -- Randall Munroe offers an amusing rhyming critique of the various majors (including math) available to undergraduates --  at xkcd.com.   And, below, I share several slightly funny math jokes adapted from ones found at Math Jokes 4 Mathy Folks and shaped into 4x4 or 5x5 syllable-square poems.

Recursion

A mathematician may face a dilemma over the meaning of an ordinary term -- for words like "group" and "identity" and "random" (to name a few) have precise mathematical definitions that differ from their common meanings. Canadian poet Peter Norman's title, "Recursion," however, uses the term as it is used mathematically.  While a definition of "recursion" is widely available in mathematics texts, it was missing in my several English dictionaries -- and I found it only in the OED (though, even there,  noted as now rare or Obs.) : "a backward movement, return."   The term "return" indicates previous forward motion. In mathematical recursion (illustrated below by the Fibonacci sequence) as in Norman's poem, going backward is possible only because forward motion is known. (Interested readers will find an introduction to mathematical recursion following the poem.)

     Recursion    by Peter Norman

     I fall awake alone. Outside,
     nocturnal rain ascends.  

The Nightmare of an Unsolved Problem

Back in the 1980s when I first met the Collatz conjecture in a number theory textbook it was stated this way:
     Start with any whole number  n :
          If  n  is even, reduce it by half, obtaining  n/2.
          If n is odd, increase it by half and round up to the nearest whole number, obtaining  3n/2 + 1/2 = (3n+1)/2.   Collatz' conjecture asserts that, no matter what the starting number, iteration of this increase-decrease process will each time reach the number 1.