### 2.2.2 Tests : `==, !=, >, >=, <, =<`

`==, !=, >, >=, <, =<` are infixed operators.
`a==b` tests the equality between `a` and `b` and returns `1` if `a` is equal to `b` and `0` otherwise.
`a!=b` returns `1` if `a` and `b` are different and `0` otherwise.
`a>=b` returns `1` if `a` is superior or equal to `b` and `0` otherwise.
`a>b` returns `1` if `a` is strictly superior to `b` and `0` otherwise.
`a<=b` returns `1` if `a` is inferior or equal to `b` and `0` otherwise.
`a<b` returns `1` if `a` is strictly inferior to `b` and `0` otherwise.
To write an algebraic function having the same result as an `if...then...else`, we use the boolean function `ifte`.
For example :

`f(x):=ifte(x>0,true,false)`

defines the boolean function f such that `f(x)= true` if x ∈ ]0;+∞[ and `f(x)=false` if x ∈ ]−∞;0].
Input :

`f(0)==0`

Output :

`1`

Look out !
`a=b` is not a boolean !!!!
`a==b` is a boolean.