Define an operator: user_operator

user_operator takes as argument :

• a string : the name of the operator,
• a function of two variables with values in $\mathbb {R}$ or in true, false,
• an option Binary for the definition or Delete to annulate this definition.

user_operator returns 1 if the definition is done and else returns 0.

Example 1
Let R be defined on $\mathbb {R}$ by x R y = x*y + x + y.
To define the law R, input :

user_operator("R",(x,y)->x*y+x+y,Binary)

Output :

1

Input :

5 R 7

Do not forget to put spaces around R.
Output :

47

Example 2
Let S by defined on $\mathbb {N}$ by :
for x and y integers, x S y < = > x and y are not coprime.
To define the law S, input :

user_operator("S",(x,y)->(gcd(x,y))!=1,Binary)

Output :

1

Input :

5 S 7

Do not forget to put spaces around S.
Output :

0

Input :

8 S 12

Do not forget to put spaces around S.
Output :

1