AI – Python Logic Programming With Example

Previously with AI, we have learned about Computer Vision, Today, we will see AI with Python Logic Programming. We will learn how to match mathematical expressions and how to check for and generate prime numbers. Also, we will see the example of Python Logic Programming.

So, let’s start the Python Logic Programming Tutorial.

What is Logic Programming in Python?

Logic programming is a way of telling the computer what we want by writing rules. In AI, this is useful when the program needs to make decisions based on facts. Python allows you to write logic-based AI using packages like PyKE and kanren. These tools help your program “think” before giving answers.

Logic programming uses statements like “if this, then that.” For example, if a person is older than 18, they can vote. Python lets you create these rules and use them to solve problems. It is very helpful in building expert systems, decision-making tools, and chatbots that work based on logic.

a. Structure of Python Logic Programming

Let’s talk about facts and rules. Facts are true statements- say, Bucharest is the capital of Romania. Rules are constraints that lead us to conclusions about the problem domain. These are logical clauses that express facts. We use the following syntax to write a rule (as a clause):

H :- B1, …, Bn.
We can read this as:
H if B1 and … and Bn.
Here, H is the head of the rule and B1, …, Bn is the body. A fact is a rule with no body:
H.

An example would be:

fallible(X) :- human(X)
Every logic program needs facts based on which to achieve the given goal. Rules are constraints that get us to conclusions.

b. Logic and Control

Think of an algorithm as a combination of logic and control.

Algorithm=Logic+Control

In a pure logic programming language, the logic component gets to the solution alone. We can, however, vary the control component for other ways to execute a logic program.

Getting Started With Python Logic Programming

Gearing up for logic programming with Python, we will install a couple of packages. Let’s use pip for this.

• Kanren- It lets us express logic as rules and facts and simplifies making code for business logic.

>>> pip install kanren

• SymPy- This is a Python library for symbolic mathematics. It is nearly a full-featured Computer Algebra System.

>>> pip install sympy

Python Logic Programming Example

With logic programming, we can compare expressions and find out unknown values. Consider the following piece of code:

>>> from kanren import run,var,fact
>>> from kanren.assoccomm import eq_assoccomm as eq
>>> from kanren.assoccomm import commutative,associative
>>> add='add' #Defining operations
>>> mul='mul'
>>> fact(commutative,mul) #Addition and multiplication are commutative and associative
>>> fact(commutative,add)
>>> fact(associative,mul)
>>> fact(associative,add)
>>> a,b,c=var('a'),var('b'),var('c') #Defining variables
>>> #2ab+b+3c is the expression we have'
>>> expression=(add, (mul, 2, a, b), b, (mul, 3, c))
>>> expression=(add,(mul,3,-2),(mul,(add,1,(mul,2,3)),-1)) #Expression
>>> expr1=(add,(mul,(add,1,(mul,2,a)),b),(mul,3,c)) #Expressions to match
>>> expr2=(add,(mul,c,3),(mul,b,(add,(mul,2,a),1)))
>>> expr3=(add,(add,(mul,(mul,2,a),b),b),(mul,3,c))
>>> run(0,(a,b,c),eq(expr1,expression)) #Calls to run()

((3, -1, -2),)

>>> run(0,(a,b,c),eq(expr2,expression))

((3, -1, -2),)

>>> run(0,(a,b,c),eq(expr3,expression))

()
You’ll see that the third expression gives us nothing. It is mathematically the same, but structurally different.

Checking for Prime Numbers in Python Logic Programming

If we have a list of numbers, we can find out which ones are prime and also generate such numbers. Let’s see how.

>>> from kanren import isvar,run,membero
>>> from kanren.core import success,fail,goaleval,condeseq,eq,var
>>> from sympy.ntheory.generate import prime,isprime
>>> import itertools as it
>>> def prime_test(n): #Function to test for prime
if isvar(n):
return condeseq([(eq,n,p)] for p in map(prime,it.count(1)))
else:
return success if isprime(n) else fail
>>> n=var() #Variable to use
>>> set(run(0,n,(membero,n,(12,14,15,19,21,20,22,29,23,30,41,44,62,52,65,85)),(prime_test,n)))

{41, 19, 29, 23}

>>> run(7,n,prime_test(n))

(2, 3, 5, 7, 11, 13, 17)

So, this was all in Python Logic Programming. Hope you like our explanation.

Conclusion

Hence, in this Python AI Logic Programming tutorial, we discussed the meaning of logic programming in Python. Moreover, we saw the example of Python Logic Programming. Also, we discussed the checking for Prime Numbers.

Still, if you have any doubt regarding Python Logic Programming, ask in the comment tab.