*Mathematical operations* are constructions used for expressing proportion (division), multiplication, addition and subtraction.

Constructions with the meaning of mathematical operations are analyzed as paratactic structures (see Section 6, "**Parataxis**"). The relation between the two parts of a paratactic structure is expressed by the functor `OPER`

(see Section 12.3, "Functor for mathematical operations and intervals (`OPER`

)") assigned to the root of the paratactic structure. The root of such a paratactic structure is the node representing the given operator (for more on operators, see Section 16.2, "Operators").

The nodes representing operands of a given mathematical operation are the terminal members of the paratactic structure. The value of their `is_member`

attribute is `1`

. Nodes that are neither operands of a mathematical operation nor delimit an interval are assigned the `0`

value in their `is_member`

attribute (see also Table 6.3, "Values of the `is_member`

attribute").

The functor of the operands corresponds to the position of the whole structure in the sentence, and is usually the same for both (all) of them.

Examples:

*Prodáváme byt 4+1. (=We are selling an appartment 4+1)* Fig. 8.199

*Přišel v 7:30. (=He came at 7:30)* Fig. 8.200

*Zápas skončil 5:0. (=The match ended 5:0)* Fig. 8.201

*obdélník 23x42 cm (=a square 23x42 cm)* Fig. 8.202

*10 mínus 2 je 8. (10 minus 2 is 8)*

**!!!** Individual types of mathematical operations will be distinguished by various subfunctors of the `OPER`

functor in the future.

**!!!** Time in the form *7 : 30* (with a colon) is represented as a mathematical operation (paratactic structure), time in the form *7.30* (with a period) is represented by a single node with the t-lemma *7.30*.