Constraints mean in an easy way

Larry sent an email to andy. andy didn't open larry's email but still understood what the message was. how did andy determine the message without opening the email?

Write a program that begins by reading in a series of positive integers on a single line of input and then computes and prints the product of those integers. integers are accepted and multiplied until the user enters an integer less than 1. this final number is not part of the product. then, the program prints the product. if the first entered number is negative or 0, the program must print “bad input.” and terminate immediately. next, the program determines and prints the prime factorization of the product, listing the factors in increasing order. if a prime number is not a factor of the product, then it must not appear in the factorization. sample runs are given below. note that if the power of a prime is 1, then that 1 must appear in t

All of the following are characteristics that must be contained in any knowledge representation scheme except