Syntax and Semantics:
Propositional logic is prohibited in its expressiveness: so just to represent true and false facts for the world. By a type of extending propositional logic to first-order logic - is calling as predicate logic and first order predicate logic - we just enable ourselves to represent much more information about the world. Moreover, as we will notice in the subsequently lecture, first-order logic enables us to reason just for the world using rules of deduction.
We will worry that first-order logic as simply a complicated language, such French or German. We will require to be able to modulate sentences from English to first-order logic, in order to give our agent in sequence about the world. Rather then we will also need to be able to translate sentences from first-order logic into English, after that we understand what our agent has deduced from the facts we gave it. Hence to do this, we will look at the combinations of symbols we are allowed to use in first-order logic for the syntax of the language too. We will require also determine how we assign meaning to the sentences in the language (the semantics), and now how we translate from one language to another still like English to Logic and vice-versa.