AndrikSeeger / Predicate_Logic_Compiler

Compiler with automated input and output for first-order predicate calculus

Compiler for first-order predicate calculus

This project is the development of a new compiler that reliably interprets and optimizes first-order predicate calculus. Therefor a new language (PREDLOG1) was created to define the logic terms as code in UTF-8.

Process

The abstract compilation process goes as follows:

1. Lexical analysis (Scanner)
2. Syntactical analysis (Parser and syntaxtree)
3. Semantical analysis
4. Code optimization
5. Final code generation

Usage

To compile the code you need:

• Flex
• Bison
• GCC
• Make

With those prerequisites met you can simply run make for the main.c file and build the compiler program. You can use the compiler to analyze your PREDLOG1-code, when using your desired file as the first input argument executing the compiled program.

Language

The language used is a new creation called "PREDLOG1" short for first-order predicate logic. The following paragraphs describe the syntax used to translate first-order predicate calculus terms to PREDLOG1.

Comments

Comments are declared using /* as in front the start of the comment and */ after the end of the comment. The comments are limited to one line per declaration.

Declarations

Every predicate, function and variable needs to be declared as follows before used:

• Predicate: DECLARE PREDICATE <id> : <arity>
• Function: DECLARE FUNCTION <id> : <arity>
• Variable: DECLARE VARIABLE <id> : int

<id> declares the identifier and <arity> declares the number of arguments.

Operands

Operand	PREDLOG1 equivalent
⇔	<->
→	->
∨	|
∧	&
¬	~
∀	ALL[<var>] or ALL [<var>]
∃	EXIST[<var>] or EXIST [<var>]
0	FALSE
1	TRUE

Priority

The order of priority is structured as follows with decreasing priority top down:

1. function
2. predicate
3. ∀,∃
4. ¬
5. ∧
6. ∨
7. →
8. ⇔

Example

/* Example PREDLOG1 */

DECLARE PREDICATE Buys : 2
DECLARE PREDICATE Pumpkin : 1
DECLARE PREDICATE Person : 1
DECLARE FUNCTION Eats : 2
DECLARE FUNCTION Carves : 2
DECLARE FUNCTION John : 0
DECLARE VARIABLE x : int
DECLARE VARIABLE y : int

EXIST[x] (Buys(John,x) & Pumpkin(x)) & ALL[x] ALL[y] (Buys(x,y) & Pumpkin(y) -> Eats(x,y) | Carves(x,y)) 
&
ALL[x] (Person(x) -> ALL[y] (Pumpkin(y) -> ~Eats(x,y))) & ~(Person(John) -> EXIST[x] Carves(John,x)) ;