The Skolem Lecture

The Skolem Lecture is an annual event in honor of the Norwegian mathematician and logician Thoralf Skolem (1887 – 1963).

Each year a distinguished scholar in mathematical or philosophical logic is invited to lecture on a topic in Skolem's spirit. The series was initiated by Professors Jens Erik Fenstad and Dagfinn Føllesdal in 1987.

Past Skolem Lectures

2022: Harry Lewis (Harvard University)

The 2022 Thoralf Skolem Memorial Lecture will be given by Harry Lewis, Gordon McKay Research Professor of Computer Science at Harvard University

Time and place: Dec. 8, 2022 1:15 PM–3:00 PM, Georg Sverdrups hus (Universitetsbiblioteket), Blindern, Auditorium 1

The Birth of Binary: Leibniz and the Origins of Computer Arithmetic

The curious history of the binary number system includes a multimillennial prehistory and a few early seventeenth-century sparks that did not catch fire. Though several others independently came up with the binary system, my recent translation and edition (with British intellectual historian Lloyd Strickland) of mostly unpublished works on binary by Gottfried Wilhelm Leibniz (1646–1716) establishes Leibniz as the key progenitor of the arithmetic used in today’s communications and computing technologies. I will review Leibniz’s research on binary notation, his increasingly sophisticated algorithms for binary arithmetic, his development of some rudiments of Boolean algebra to describe his calculus symbolically, his improvisation of a concatenation semigroup to describe patterns in bit strings, his plans for two different binary calculators, and his invention of what we now call hexadecimal notation, complete with four different notations for the hex digits, including the one in general use today. I will also comment on Leibniz’s efforts to universalize his invention by connecting it to Christian and Chinese traditions.

About Harry Lewis

Harry Lewis, Gordon McKay Research Professor of Computer Science at Harvard University, holds AB and PhD degrees in Applied Mathematics from Harvard. A member of the Harvard faculty since 1974, he has helped launch thousands of Harvard undergraduates, including both Bill Gates and Mark Zuckerberg, into careers in computer science. Principal architect of Harvard’s undergraduate computer science program, he served as Dean of Harvard College and interim dean of Harvard’s Engineering School and was the recipient of the IEEE’s 2021 Mary Kenneth Keller Computer Science & Engineering Undergraduate Teaching Award. His recent books include an edited collection of classic computer science papers, “Ideas that Created the Future,” as well as “Leibniz on Binary” with Lloyd Strickland, both published by MIT Press.

2019: Steve Awodey (Carnegie Mellon University)

The Skolem lecture 2019 was given by Professor Steve Awodey of Carnegie Mellon University.

Time and place: Apr. 25, 2019 10:15 AM–12:00 PM, Georg Morgenstiernes hus, room 652

Univalence, Invariance, and Intensionality

What does a mathematical proposition mean? Under one standard account, all true mathematical statements mean the same thing, namely True. A more meaningful account is provided by the Propositions-As-Types conception of type theory, according to which the meaning of a proposition is its collection of proofs. The new system of Homotopy Type Theory provides a further refinement: The meaning of a proposition is the homotopy type of its proofs. A homotopy type may be seen as an infinite-dimensional structure, consisting of objects, isomorphisms, isomorphisms of isomorphisms, etc. Such structures represent systems of objects together with all of their higher symmetries. The language of Martin-Löf type theory is an invariant of all such higher symmetries, a fact which is enshrined in the celebrated Principle of Univalence.

Skolem Lectures 1987-2016

  • 2016 Stewart Shapiro
  • 2015 Michael Rathjen
  • 2014 Kit Fine
  • 2013 Peter Aczel
  • 2011 Jan von Plato
  • 2010 William Tait
  • 2007 Stan S. Wainer
  • 2006 Göran Sundholm
  • 2005 Thierry Coquand
  • 2004 Tim Williamson
  • 2002 Paul Cohen
  • 2001 Saul Kripke
  • 2000 Krister Segerberg
  • 1999 Peter Gärdenfors
  • 1998 Helmut Schwichtenberg
  • 1997 Dana Scott
  • 1996 Per Martin-Löf
  • 1995 Charles Parsons
  • 1994 Grigori Mints
  • 1993 Hao Wang
  • 1992 Jean Yves Girard
  • 1991 Burton Dreben
  • 1990 Robert Boyer
  • 1989 Solomon Feferman
  • 1988 Robin Gandy
  • 1987 Dag Prawitz