25-05-2012, 03:39 PM
Challenges for Biologically-Inspired Computing
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ABSTRACT
We discuss a number of fundamental areas in which biologically
inspired computing has so far failed to mirror biological reality.
These failures make it difficult for those who study biology (and
many other scientific fields) to benefit from biologically inspired
computing. These areas reflect aspects of reality that we do not
understand well enough to allow us to build adequate models. The
failures-to-date are as follows.
INTRODUCTION
Although there is now a complex network of conferences and
journals through which flows a torrent of biologically inspired
computing papers, a number of fundamental modeling problems
(listed in the abstract) remain unsolved.
The problems pertain to the following interconnected collection of
issues. Please note that the following list covers ground which is
similar to the list in the abstract, but it isn’t exactly the same list,
and the issues are not covered in the same order.
NIHIL EX NIHILO: HOW COMPUTER SCIENCE ORIGINATED THE PROBLEM, AND HOW IT HAS PERPETUATED IT
Nothing operates for free: nihil ex nihilo. One can’t get a
computational process from nothing. To run a computer program
(or any computation) in the real world one needs a process
powered by a source of energy.
Yet in computer science we typically assume that we can create
abstract computational devices or processes from nothing. We
say: let T = <…> be a Turing Machine, or let F = <…> be a finite
automaton, or let P = … be a computer program. We then proceed
to analyze how that Turing Machine, finite automaton, or
computer program would operate.
Computing as Stigmergy, an Emergent
Process
Turing Machines are fine for analyzing computability, but when
we use them as our basic framework for thinking about
fundamental real world computational issues we ignore the fact
that in reality a computation exists only if there is some energydriven
process that is doing the computing. In the real world, such
computing processes are typically provided by the operation of a
general purpose computer. Therefore it is worth looking briefly at
how a general purpose computer creates a computation.
In simplest terms, a general purpose computer is simply a device
that executes individual (machine) instructions, one after another.
There are only a finite number of operations5 that a general
purpose computer is capable of performing, and each one is
generally quite simple. No one instruction is an algorithm
execution6. An algorithm execution results when a sequence of
instructions is executed. That algorithm execution is not built into
the computer. It is an emergent phenomenon in much the same
way that a glider is an emergent phenomenon in the Game of Life.
FITNESS
If our world is a world primarily of processes (rather than of
things), a central question is what keeps the processes running.
Clearly the answer is that processes operate only when they have
access to sufficient energy and materials to maintain themselves.
Our basic model then is of a world of process entities (not
necessarily biological) that must “consume” (in some loose
general sense) energy and materials that they find in their
environment in order to sustain and perpetuate themselves.
SUMMARY
Ten years ago, Steven Weinberg used [20] the weather as an
example to make the anti-emergence anti-entity case.
what might be called extreme reductionism.