user_operator takes as argument:
user_operator returns 1 if the definition is done and else returns 0.
Example 1
Let R be defined on ℝ by x R y= x*y+x+y.
To define the law R, input:
Output:
Input:
Do not forget to put spaces around R.
Output:
Example 2
Let S be defined on ℕ by:
for x and y integers, x S y <=> x and y are not coprime.
To define the law S, input:
Output:
Input:
Do not forget to put spaces around S.
Output:
Input:
Do not forget to put spaces around S.
Output: