Lecture-02-Prolog-Introduction.pdf

🖋 Notes

Prolog language

Intro

• wide range of applications: relational databases, artificial intelligence, mathematical logic, proof of theorems, expert systems, solving abstract problems or symbolic equations, etc
• No standard for object-oriented programming in Prolog, there are only extensions: TrincProlog, SWI-Prolog
• SWI-Prolog
  • provides a two-way interface with C and Java languages
  • uses XPCE -an object oriented GUI system
  • multithreading - based on the multithreading offered by the standard C language

Prolog Program

• has descriptive character
• is a collection of definitions that describe relationships or functions to be calculated (symbolic representations of objects and relationships between objects)
• the solution to the problem is no longer seen as a step-by-step execution of a sequence of instructions
• Prolog uses (linear) resolution to prove whether the conclusion (theorem) is true or not, starting from the hypothesis established by the defined facts and rules (axioms)
• reasoning is applied backwards to demonstrate the conclusion
• the program is read from top to bottom, from left to right, the search is depth-first and is done using backtracking

Elements of the SWI-Prolog language

Term

1. Simple:

   1. constant
      • symbol
        • sequence of letters, numbers, …
        • start with a lowercase letter
      • number
        • integer, real (number)
      • string
        • 'text' (character: 'c', '\t', ...)
      • special characters
        • • • / <> =:. & _ ~

   ATOM = SYMBOL + NUMBER + STRING + SPECIAL-CHARACTERS + [] (empty list)

2. variable

   1. sequence of letters, number starting with a capital letter
   2. the anonymous variable is represented by the underline character (_)

3. Compound: