Ravenbrook Ravenbrook is a software engineering consultancy. Our goal is to increase the value of the software industry to society.

Arthur Lemmens

Senior Consultant.


  • Common Lisp programming and software design.
  • Machine translation.
  • Educational software and in particular language learning.
  • Artificial intelligence.
  • Social network analysis.
  • Commercial databases.


I have been an independent software consultant since 1993. Recent contracts have included:

  • 2011-2013: Ravenbrook: Social Network Analysis software.
  • 2010: Thingamy Ltd: Adding a REST API to Thingamy business software.
  • 2009-2010: European Patent Office (Rijswijk, The Netherlands): European Machine Translation Project.
  • 2008-2011: Remerie Bouw (Amsterdam, The Netherlands): Building design software.
  • 2007: Clozure Associates, ITA Software (Cambridge, MA, USA): Airline reservation and departure control system.
  • 2006: Ravenbrook: Artificial Intelligence simulations.
  • 2005: Q Software Solutions GmbH (Germany): CLIM/HTML Lisp library.
  • 2004-2006: Franz Inc (Oakland, California, USA): CLIM (Common Lisp Interface Manager) support.
  • 2001-now: University of Wageningen (NL): Tree growth simulations.
  • 2000-2002: Coutinho Publishers (Bussum, NL): Educational software.

Previous jobs involved: database design, language learning and other educational software, web servers.


No formal education after secondary school. Obtained computer science diploma (in 1989) by self study and taking Dutch state exams (AMBI) at higher educational level.

Programmer community activities


Performance of trees in forest canopies: explorations with a bottom-up functional-structural plant growth model” by F.J. Sterck, F. Schieving, A. Lemmens, T.I. Pons (New Phytologist, 2005)


Apart from Common Lisp, I have written software in Basic, C, C++, Javascript, Mathematica, Pascal, Scheme and various assembler languages. When necessary, I read programs in languages like Fortran, Prolog or Python.

I enjoy learning languages. Dutch is my native language and I use English every day at work, but I also speak and read French, German, Russian, Spanish and Japanese (at JLPT 1 level).

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