Perkun hidden variables.

We do not perceive directly everything that is happening in the world. Or to say it otherwise - in order to understand the world it is useful to imagine that some facts about it remain hidden. Likewise - in Perkun (http://sourceforge.net/projects/perkun/) it is assumed that the world has a state described by the visible variables (so called input variables) and by the invisible variables (so called hidden variables). How to declare them in Perkun?

values { value false, true; }
variables 
{
    input variable a:{false, true}, b:{false, true};
    hidden variable c:{false, true}, d:{false, true};
}
payoff {}
model {}
cout << variables << eol;

The above Perkun code defines two input variables (a and b) and two hidden variables (c and d). All of them may have either value false or true. When you run it with perkun it will write out:

# variables
input variable a:{false,true};
input variable b:{false,true};
hidden variable c:{false,true};
hidden variable d:{false,true};

But how can we use the hidden variables? What is it good for, to take into account the variables we do not perceive? Well, in order to understand this we need to learn how to use the model section of the Perkun program. It will be described in the next post.