
(..Statement Part)	Contents	Index	(Declaration Part..)

4. SDL - Sigma Definition Language

In this chapter we are going to discuss the second programming language, which is also an integral part of SCARLET, the so-called Sigma Definition Language (SDL). It deals with the typical behaviour of a CA, which is given by its local rule, a function often called . (This is, by the way, the reason for the name of the language).
To be able to design a local rule in SCARLET, we have to know

the dimension of the space,
the state set (that means, kind and number of used registers)
the neighbourhood
the boundary value (here: the state, common to all cells on the border)

Unlike this, the extension of the retina or even its initial configuration are not relevant in this context. Because of that, indications concerning the retina are saved in a separate file as a RDL program. (This has already been the topic of the preceding chapter.)
Later a complete CA will be constructed by SCARLET using the information of a RDL program as well as of a compiled SDL program. What are exactly the conditions to grant the compatibility? We are going to see that in the last paragraph of this chapter.

Giving a look to the typical structure of a SDL program, we recognize immediately that it is - like RDL programs - subdivided into two main parts: the declaration part and the table part:

Sigma - Syntax:


(..Statement Part)	Contents	Index	(Declaration Part..)