# Boolean Expressions

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## 1 Introduction

Boolean expressions can be used to perform logical operations that return either true or false.

## 2 and

The `and` operator checks two Boolean expressions and only returns `true` if both of the expressions are true.

### 2.1 Examples

The examples below illustrate which value the expression returns:

• If you use the following input:

``````(6 > 4) and (3 < 5)
``````

The output is `true` because both of the expressions are `true`.

• If you use the following input:

``````('hello' = 'hallo') and (3 < 5)
``````

The output is `false`, because only the second expression is `true`.

## 3 or

The `or` operator combines two Boolean expressions, and returns `true` if at least one of the expressions is true.

### 3.1 Examples

The examples below illustrate which value the expression returns:

• You have a entity called product that has the price attribute of the integer type. The price attribute equals 3, and you have another attribute called recommendedPrice that equals 2.

If you use the following input:

``````(\$product/price < \$product/recommendedPrice : 2) or (\$product/price     > 0)
``````

The expression will return `true` because at least one of the expressions is true (the second one). Note that the expression would still return `true` if both statements had been true.

• If you use the following input:

``````('hello' = 'nothello') or ('byebye' = 'stillnotbyebye')
``````

The expression will return `false`, because both expressions are false.

## 4 not

The `not` operator negates the specified Boolean expression.

### 4.1 Input

An expression of type Boolean.

### 4.2 Output

Returns the negation of the specified expression. If the expression evaluates to `true`, it returns `false`; and vice versa.

### 4.3 Examples

The examples below illustrate which value the expression returns:

• If you use the following input:

``````not('hello' = 'hallo')

``````

The expression will return `true` .

• If you use the following input:

``````not(true)
``````

The expression will return `false` .