For Virus Project 2.0 Nechvatal (with the help of his
programmer/collaborator Stťphane Sikora) took Nechvatalís 1992-3 virus
project 1.0 into the realm of artificial life (i.e. into a synthetic system
that exhibits behaviors characteristic of natural living systems Ė in his
case viruses). For virus project 2.0, an A-life virus program is unleashed
on image-files from Mr. Nechvatalís recent body of work; "ec-satyricOn 2000
(enhanced)+ bodies in the bit-stream(compliant)". Also on view was a
Director animation documenting Nechvatalís Computer Virus Project 1.0 and
recent digital prints by Nechvatal.
Joseph Nechvatalís 2001 Computer Virus Project 2.0 follows along the same
lines as previous viral works by Nechvatal in 1992 - works where an
unpredictable progressive virus operates on a degradation/transformation of
an image. Now, using a C++ framework, elements of artificial life have been
introduced in that viruses are modeled to be autonomous agents living in/off
the image. The project simulates a population of active viruses functioning
as an analogy of a viral biological system. Here viral algorithms - based
on a viral biological model - are used to define evolutionary processes
which are then applied to image-files from Nechvatalís "ec-satyricOn 2000
(enhanced)+ bodies in the bit-stream (compliant)" series. Among the
different techniques used here are models that result from embodied
artificial intelligence and the paradigm of genetic programming.
The Model : Notes by Stťphane Sikora / Joseph Nechvatal
The world is modeled as an image via a set of pixels. Every pixel's color is
defined by R,G,B real number vectors which represent the red, green and blue
components of every pixel's color.
The image world has no edges. Every square on the edge of the image is
adjacent to another on the opposite edge. A virus can move around the image
and impact the image world as different colors actually correspond to
resources used for survival by the viruses.
The Virusís Behavior
The behavior of a virus is modeled as a generated looping activity that is
typical of situated artificial intelligence work. A virus will pick up
information from its environment, decide on a course of action, and carry it
out. The loop is simplified here because of the abstract character of the
simulacrum. Viral instructions provide different possibilities for executing
instructions according to the environmental conditions in which the virus is
A virus will perceive the pixel it is on and the eight adjacent ones. It can
get information on its color and on the possible presence of other viruses.
In order to decide on a course of action, each virus is programmed with a
set of randomized instructions of different kinds; some relate to direction,
others to a change in the color of the current pixel (the one the virus is
in). Others control the implementation of the program and carry out tests.
Once the program has been executed, following actions to be carried out
randomly arise. As the virus executes them, it moves to one of the adjacent
squares and changes the current pixel. It can even reproduce itself
(reproduction here results from the instruction 'divide'. A virus that
carries out that instruction will produce a replica of itself - although
slightly altered. Its genome-program changes with the mutation operator).
In addition to these changes, every cycle produces a change in the energy
level of the virus. The virus will lose a set amount of energy with every
run, and when it runs out of energy, it dies (i.e. it disappears). In order
to survive, a virus needs to pick up energy, which it can only do by
degrading the image. The more it changes the color of a pixel, the more
energy it acquires. The difference between the color before and after is
We can see from a virusís behavior and direction whether it will be more or
less adaptable - more or less able to survive.
There is a maximum number of viruses that can be present simultaneously
(usually 1000). When that number is reached, the 'divide' instruction is
ignored. If the virus has enough energy it will move around randomly,
otherwise it will follow its favorite color and absorb part of the red
component of the pixel it is on.
The Dynamics of the System
A viral attack will generally develop as follows:
a) A world is created from an image.
b) A population of viruses is generated randomly and introduced into the
image. Every virus takes on its very own behavior, as the program defines
c) Once the viruses have been placed in an image, the attack can start. It
will consist of a series of action cycles that will only come to an end when
there is no virus left alive (or after a given time limit).
Many different dynamics can be seen that depend on the parameterization of
the experiment. For example:
a) Filtering : The viruses act as local filters on the image. The
modification of a pixel's color will influence the subsequent dynamics, and
it can influence the virusís demeanor and its trajectory. For example, a
virus attracted by the intensity of the red component in pixels reduces the
intensity of the color if it executes 'eat red' - and will tend to avoid the
areas it has already visited. In order to have some control over the global
effect, Joseph Nechvatal can define a set of active instructions; those
which will be part of the genome program for the virus.
b) Reproduction, Evolution, and Adaptation : The instruction 'divide' will
reproduce replicas of a virus (slightly different through mutation). The
creation of these replicas will immediately trigger a considerable loss of
energy in the virus. This means that a virus that is not capable of drawing
energy from its environment will not survive much longer after it has
carried out the 'divide' mandate. And so will its replicas.
On the other hand, the fact that these replicas are not identical to the
original offers the possibility of examining new types of behavior.
When an adapted individual appears, it can remain in the image for quite
some while. If it executes the 'divide' instruction, its descendants will
most probably be equally adapted. The number of these agents will generally
increase exponentially, and thereby create a large population of very active
For more information on Computer Virus Project 1.0, see: