We have already discussed how Constraint Satisfaction Problems are formulated. Let's apply them to a real-world problem. In this problem, we have a list of names and each name can only take a fixed set of values. We also have a set of constraints between these people that needs to be satisfied. Let's see how to do it.

Create a new Python file and import the following packages:

from simpleai.search import CspProblem, backtrack, \ 
    min_conflicts, MOST_CONSTRAINED_VARIABLE, \ 
    HIGHEST_DEGREE_VARIABLE, LEAST_CONSTRAINING_VALUE 

Define the constraint that specifies that all the variables in the input list should have unique values:

# Constraint that expects all the different variables  
# to have different values 
def constraint_unique(variables, values): 
    # Check if all the values are unique 
    return len(values) == len(set(values))   

Define the constraint that specifies that the first variable should be bigger...