How Many AI People Does It Take To Change A Lightbulb

How Many AI People Does It Take To Change A Lightbulb

[the original was posted in the early 1980s by Jeff Schrager, then a PhD student at CMU]

Q: How many Artificial Intelligence (AI) people does it take to
change a lightbulb?

A: At least 55:

The problem space group (5): [

  • One to define the goal state,
  • One to define the operators,
  • One to describe the universal problem solver,
  • One to hack the production system,
  • One to indicate about how it is a model of human lightbulb changing behavior


The logical formalism group (16): [

  • One to figure out how to describe lightbulb changing in first order logic,
  • One to figure out how to describe lightbulb changing in second order logic,
  • One to show the adequacy of FOL,
  • One to show the inadequacy of FOL,
  • One to show that lightbulb logic is non-monotonic,
  • One to show that it isn’t non-monotonic,
  • One to show how non-monotonic logic is incorporated in FOL,
  • One to determine the bindings for the variables,
  • One to show the completeness of the solution,
  • One to show the consistency of the solution,
  • One to show that the two just above are incoherent,
  • One to hack a theorem prover for lightbulb resolution,
  • One to suggest a parallel theory of lightbulb logic theorem proving,
  • One to show that the parallel theory isn’t complete. …ad infinitum (or absurdum, as you will). …
  • One to indicate how it is a description of human lightbulb changing behavior,
  • One to call the electrician


The robotics group (10): [

  • One to build a vision system to recognize the dead bulb,
  • One to build a vision system to locate a new bulb,
  • One to figure out how to grasp the lightbulb without breaking it,
  • One to figure out how to make a universal joint that will permit the hand to rotate 360+ degrees,
  • One to figure out how to make the universal joint go the other way,
  • One to figure out the arm solutions that will get the arm to the socket,
  • One to organize the construction teams,
  • One to hack the planning system,
  • One to get Westinghouse to sponsor the research,
  • One to indicate about how the robot mimics human motor behavior in lightbulb changing


The knowledge engineering group (6): [

  • One to study electricians’ changing lightbulbs,
  • One to arrange for the purchase of the lisp machines,
  • One to assure the customer that this is a hard problem and that great accomplishments in theory will come from his support of this effort (The same one can arrange for the fleecing.),
  • One to study related research,
  • One to indicate about how it is a description of human lightbulb changing behavior,
  • One to call the lisp hackers


The Lisp hackers (13): [

  • One to bring up the chaos net,
  • One to adjust the microcode to properly reflect the group’s political beliefs,
  • One to fix the compiler,
  • One to make incompatible changes to the primitives,
  • One to provide the Coke,
  • One to rehack the Lisp editor/debugger,
  • One to rehack the window package,
  • Another to fix the compiler,
  • One to convert code to the non-upward compatible Lisp dialect,
  • Another to rehack the window package properly,
  • One to flame on BUG-LISPM,
  • Another to fix the microcode,
  • One to write the fifteen lines of code required to change the lightbulb


The Psychological group (5): [

  • One to build an apparatus which will time lightbulb changing performance,
  • One to gather and run subjects,
  • One to mathematically model the behavior,
  • One to call the expert systems group,
  • One to adjust the resulting system, so that it drops the right number of bulbs


Thank you, Jack

Notes from “A Celebration of the Life of Jacob T. Schwartz” at NYU on Friday 27 March 2009

A few notes that I took during the celebration. These notes are expected to be read along with scanned image of the program, included as a PDF file. Jack’s widow Diana added some comments to my notes, which are included in italics with the prefix “DS”.

The program takes the form of a SETL program.
DS: I put this together in tribute to SETL. I think he would have loved it.

The MC was Ed Schonberg. There was a brief greeting by the head of Courant.
DS: I asked Ed to be the MC since he coordinated Jack’s 70th birthday festschrift.

Marian McPartland performed two pieces on the piano. She clearly knew and cared for Jack and Ed.
DS: I came to NY 35 years ago with a scholarship to study jazz piano with Marian. She and I quickly became friends and have been close friends for many years. When I married Jack she instantly was drawn to him and they used to have the most amazing conversations. Jack, knowing nothing about jazz and Marian knowing nothing about mathematics and computer science. It was wonderful to witness.

The first speaker was Judith Dunford, Jack’s sister. She talked about her relationship with Jack and his generosity. She talked about his multifarious interests and his enthusiasm for many subjects and his eagerness to share them with her. His devotion and loyalty to her and her children.

Martin Davis spoke next – he and Jack were undergrads at City College together and spent a summer painting Jack’s parents’ apartment in the Bronx while reading lots of mathematics.

David Finkelstein – the third member of the mathematics and apartment painting crew from 1949.

The program has David Robinson performing on the guitar, but the actual performance came after Louis Nirenberg.
DS: David Robinson is my brother and a professional guitarist in Scottsdale, Arizona. He played one of Jack’s favorite Bach pieces.

Louis Nirenberg, who knew Jack from his arrival at the NYU mathematics department, spoke next. He talked about Jack’s broad range of interests, recounting how Jack had played Eskimo music at a party at his apartment. “What you give the man who has heard everything.”

David Robinson performed Bach on the guitar.

Fran Allen spoke about her life with Jack in the context of various journeys and travels and all of the interesting people they hosted in their apartment and aboard the houseboat when they lived at the 79th Street boat basin. She noted that when she first met Jack a colleague pointed him out to her and noted, “that’s a great man.”

Sue Merritt was next, but she said, “I didn’t know I was on the list.”
DS: This was my fault. Jack gave the commencement address at Pace two years ago, organized by Sue. They were good friends. Fran told me that she would speak with Sue about speaking but it somehow fell through the cracks. We were all pretty crazed during this period, as you can imagine.

Greg Chaitin talked about a visit by a bunch of mathematicians to Buenos Aires when he was a young programmer working there for IBM. Jack noticed a short presentation he made and urged him to come to New York and study at Courant.

Robert Dewar was working on the Plato system when Jack met him on a site visit. Jack subsequently called him up and invited him to come to the new Courant CS department and be the chair. He quoted Jack on administration: “There are two kinds of administrators. One kind says ‘no’ to all requests in order to avoid trouble. The other says ‘yes’ to all requests and then gets someone else to sort things out if there is trouble.” He noted that Jack was clearly the ‘yes’ kind and that he had modeled himself on Jack’s style. Robert recounted that early in their friendship he’d said to Jack that he wished that he’d learned more about economics. Jack replied that he’d found the field disappointing. Robert subsequently discovered that Jack had written something like five books on economics, including “The Theory of Money.”

Michael Schwartzman recounted how Jack had worked to help him escape from the USSR. He spoke movingly about his relationship with Jack and his feelings for him.

Ed Schonberg performed parts of Brahms’ “Variations on a Theme by Handel” on the piano.
DS: Jack loved the way Ed played these variations and asked Ed to play them at our apartment whenever he visited.

Alfredo Ferro (I think … my notes are confused at this point) spoke at length about how Jack had started the field of Computable Set Theory and was the academic grandfather of a vast army of mathematicians in Italy working in the field.
DS: Only Eugenio Omodeo spoke. Alfredo was there but was too emotional to speak.

Bud Mishra talked about Jack and robotics.

Ed Schonberg read a letter from Jack’s co-author on the piano mover papers.
DS: Micha Sharir who lives in Tel Aviv could not come but sent the email instead.

Ken Perlin talked movingly about Jack’s move into multimedia and his mentorship. He announced the endowment in Jack’s name of an annual $5,000 prize for an outstanding undergraduate in multimedia, giving $30,000 of his own money and soliciting donations for the rest of the $100,000 required to fund the prize in perpetuity.
DS: Ken has been able to raise the necessary money so the prize exists.

Adrienne Fainman, one of Jack’s granddaughters, spoke very movingly. She told how Jack had convinced her that pigeons love blueberry muffins above all other food. She talked about her sessions learning math with him and how he’d say, “This is a beautiful proof,” stretching out the first vowel in beautiful. She quoted him as explaining to her that “if you’re confused, then you’re going to learn something.”

Peter Lax told us to go out and read a short humorous/serious essay of Jack’s called, “The Pernicious Influence of Mathematics in Science.”
DS: This is on Jack’s personal website:

Michael Rabin was the final speaker. He talked about Jack the man. He noted that Jack’s observations about people were “always penetrating, but never malicious.” He noted that Jack had written an illustrated book for children, “Relativity in Illustrations.” He described a talk that Jack had given at Harvard four years ago on textures in graphics.

This was the end of the formal program. At this point a man named Sal Anastasio spoke up and came forward. He recounted very movingly how, in his mid-20s, he’d come to NYU to study mathematics. He had been a high school math teacher and what he wanted above all else was to teach teachers. He describe how he’d studied with Jack and how Jack had rescued his PhD candidacy in various ways. He has spent the last thirty or more years teaching aspiring high school teachers up at SUNY New Paltz, something that would have been impossible without Jack’s patronage.

Diana Schwartz then performed a composition of her own titled “Portrait of Jack” on the piano.

Karen Morissey then sang a beautiful and moving song “The Parting Glass.”
DS: Karen and I have been friends for 30 years. She and I used to perform in jazz clubs together in NYC. Jack loved her voice and the way she sang this Irish ballad.