COP 3223H meeting -*- Outline -*-

* Friday Problems with Boolean Expressions and Predicates

** implication function
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           FOR YOU TO DO

1. Write a function, implies(b1, b2),
that takes two bool arguments, b1 and b2,
and returns True just when b1 implies b2.
That is, it returns true just when either
not b1 or b2 is True.







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** printing truth tables for arbitrary functions
     In Python, you can pass functions as arguments!
     
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         FOR YOU TO DO

2. Write a procedure, print_truth_table(p),
   that takes a 2-argument Boolean predicate,
   p, as an argument, and prints a truth
   table for p that displays the value
   of p(b1, b2) for all pairs of Booleans
   b1 and b2.

For example,
   print_truth_table(implies)
would print on stdout:

arg1\arg2 | True  | False
    True  | True  | False
    False | True  | True

For another example, suppose we have:

def notOrDM(b1, b2):
    return not (b1 or b2) == not b1 and not b2

Then print_truth_table(notOrDM)
would print on stdout:

arg1\arg2 | True  | False
    True  | True  | True
    False | True  | True













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    It may be helpful to have a procedure that prints a bool in 6 spaces.

def printB6(b):
    """Print b on stdout in 6 spaces, left aligned, with no trailing newline."""
    if b:
        print("True  ", end='')
    else:
        print("False ", end='')
      
    How to solve problems like this?
    Imagine that the function parameter is something specific, solve
    for that, then generalize.

** tautologies
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             FOR YOU TO DO

3. Write a function, is_tautology(p),
   that takes a 2-argument Boolean predicate,
   p, as an argument and returns True just
   when p is a tautology.
   That is is_tautology(p) returns True
   just when p(True,True), p(True, False),
   p(False, True), and p(False, False) are
   all True.








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