Boolean operators: or xor and not

### 6.1.4 Boolean operators: or xor and not

Booleans can be combined to form new booleans. For example, with and: the statement “boolean 1 and boolean 2” is true if both boolean 1 and boolean 2 are true, otherwise the statement is false.

Xcas has the standard boolean operators, as follows (a and b are two booleans):

or (or ||)
  These are infixed operators. (a or b) (or (a || b)) returns 0 (or false) if a and b are both equal to 0 (or false) and returns 1 (or true) otherwise.
xor
  This is an infixed operator. It is the “exclusive or” operator, meaning “one or the other but not both”. (a xor b) returns 1 if a is equal to 1 and b is equal to 0 or if a is equal to 0 and b is equal to 1, and returns 0 if a and b are both equal to 0 or if a and b are both equal to 1.
and (or &&)
  These are infixed operators. (a and b) (or (a && b)) returns 1 (or true) if a and b are both equal to 1 (or true) and returns 0 (or false) otherwise.
not
  This is a prefixed operator. not(a) returns 1 (or true) if a is equal to 0 (or false), and 0 (or false) if a is equal to 1 (or true).

Examples.

- Input:
  1>=0 or 1<0
  Output:

  1

- Input:
  1>=0 xor 1>0
  Output:

  0

- Input:
  1>=0 and 1>0
  Output:

  1

- Input:
  not(0==0)
  Output:

  0