# Section 7.2.2:
BOOL

###### immutable class BOOL

See also the Required Library class BOOL which provides a full range of logical operators as well as text and other conversion features in addition to those defined for this pervasive class.

#### Formal Types

types
SAME = BOOL ;
BOOL = bool

#### not

This feature provides the standard Boolean inversion operation.

not | : SAME

##### Formal Signature

The name of the formal operation corresponding to 'not' has been modified since the word 'not' is a keyword in vdm-sl.

not_v(self : SAME) res : SAME

##### Post-condition

post res = not self

This feature returns the logical complement of self.

#### and

This feature provides the Boolean conjunction operation.

and | (
| other : SAME
| ) : SAME

##### Formal Signature

The name of the formal operation corresponding to 'and' has been modified since the word 'and' is a keyword in vdm-sl.

and_v(self : SAME, other : SAME) res : SAME

##### Post-condition

res = (self
and other)

This routine returns true if and only if self and other are both true, otherwise false.

#### or

This feature provides the operation of logical disjunction.

or | (
| other : SAME
| ) : SAME

##### Formal Signature

The name of the formal operation corresponding to 'or' has been modified since the word 'or' is a keyword in vdm-sl.

or_v(self : SAME, other : SAME) res : SAME

##### Post-condition

post res = (self
or other)

This routine returns true if and only if either self or other or both are true, otherwise false.

#### is_eq

This feature provides the logical equality operation for Boolean values. It may be used in infix logical expressions.

is_eq | (
| other : SAME
| ) : SAME

##### Formal Signature

is_eq(self : SAME, other : SAME) res : SAME

##### Post-condition

post res = (self
= other)

This routine returns true if and only if both self and other have the same value, otherwise false.

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