General Explanation Formulae
Formulae are expressions of predicate logic that can be interpreted as true or false according to the defined World. Properties are characteristics of single individuals.Therefore, if the expression is a property only one individual can stand in the brackets behind the expression e.g. blonde(Alice). Relations exist between more than one individual. Mostly the relations are two-sided. Therefore, if the expression is a two-sided relation, two individuals need to stand in the brackets behind the expression e.g. father of someone(Paul,Lisa). If the relations are more than two-sided, the number of individuals in brackets simply increases. Weather the interpretation of a formula is true or false does not have an influence on the formula itself. It stays a formula.