The principle of the permutable reposes son the possible variation of geometric elements inside a structured composition.
Permutable "Chromatic Square - 1975"
We depart from a chromatic square composed
of yellow, blue and red triangles which are part of a larger
square containing four identical chromatic squares forming a
total of sixteen elements and which are accepted as the basic
composition.
A computer program generating random numbers
determines and codifies successively the number of elements of
a given square composition as well as the position, the size
and the colour or absence of colour of the elements in question.
In the chromatic square, two adjacent triangles will form their
resulting colour, for example red + yellow = orange, etc the
addition of three colour triangles form grey, from light grey
to black according to their number.
In this manner we constructed 64 random
chromatic squares which form the original alphabet of the present
permutable. Next figure shows a few examples of the series.
#02
#12 
#22
#32
#42 
#52
This alphabet allows us to construct structured combinations
comporting several randomly determined chromatic squares.
In a structured combination a multitude
of other combination are possible by varying the position if
the chromatic squares as well as their orientation.
A work of 220x350cm composed of 16 permutables painted on resin
covered wooden panels.
Permutable "Esschius -1975" (limited edition of 30 )
Another type of permutable of the same period was executed with
computer generated geometric structures based on the division
of the square.
In 90 randomly chosen drawings, of a population
of 72! (factorial 72), on white, grey and black cardboard, the
resulting "window forms were cut out.
The grey, white and black cut-out cardboard
which may be oriented at will to form multiple (220) combinations
are superposed and framed.
