TITLE: The Suffocating Gerbils Problem
AUTHOR: Eugene Wallingford
DATE: September 12, 2014  1:49 PM
DESC: 
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BODY:
I had never heard of the "suffocating gerbils" problem until I
ran across
<A HREF="http://lambda-the-ultimate.org/node/563#comment-4544">
   this comment</A>
in a Lambda the Ultimate thread on mixing declarative and
imperative approaches to GUI design.  Peter Van Roy explained
the problem this way:

<BLOCKQUOTE><EM>
 A space rocket, like the Saturn V, is a complex piece of
 engineering with many layered subsystems, each of which
 is often pushed to the limits.  Each subsystem depends
 on some others.  Suppose that subsystem A depends on
 subsystem B.  If A uses B in a way that was not intended
 by B's designers, even though formally B's specification
 is being followed by A, then we have a suffocating gerbils
 problem.  The mental image is that B is implemented by a
 bunch of gerbils running to exhaustion in their hoops.  A
 is pushing them to do too much.
</EM></BLOCKQUOTE>

I first came to appreciate the interrelated and overlapping
functionality of engineered subsystems in graduate school,
when I helped a fellow student build a software model of
the fuel and motive systems of an F-18 fighter plane.  It
was quite a challenge for our modeling language, because
the functions and behaviors of the systems were intertwined
and did not follow obviously from the specification of
components and connections.  This challenge motivated the
project.  McDonnell Douglas was trying to understand the
systems in a new way, in order to better monitor performance
and diagnose failures.  (I'm not sure how the project turned
out...)

We suffocate gerbils at the university sometimes, too.  Some
functions depend on tenure-track faculty teaching occasional
overloads, or the hiring of temporary faculty as adjuncts.
When money is good, all is well.  As budgets tighten, we
find ourselves putting demands on these subsystems to meet
other essential functions, such as advising, recruiting, and
external engagement.  It's hard to anticipate looming
problems before they arrive in full failure; everything is
being done according to specification.

Now there's a mental image: faculty gerbils running to
exhaustion.

If you are looking for something new to read, check out some
of Van Roy's work.  His
<A HREF="http://www.info.ucl.ac.be/~pvr/book.html">
   Concepts, Techniques, and Models of Computer Programming</A>
offers all kinds of cool ideas about programming language
design and use.  I happily second the sentiment of
<A HREF="https://twitter.com/asolove/status/510064427413274624">
   this tweet</A>:

<BLOCKQUOTE><EM>
 Note to self: read all Peter Van Roy's LtU comments in
 chronological order and build the things that don't
 exist yet:
 <A HREF="http://lambda-the-ultimate.org/user/288/track?from=120&sort=asc&order=last%20post">
    http://lambda-the-ultimate.org/user/288/track?from=120&sort=asc&order=last%20post</A>
</EM></BLOCKQUOTE>

There are probably a few PhD dissertations lurking in those
comments.
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