Entity$/$Attribute Model:

Provide examples for each type$/$property and its variations on a small example of $3-4$ entities and attributes. Explain the concepts, their variations, properties of entities $($with several attributes$),$ and relationships between them for a database.

Explain natural join $-$ entity, designations, properties. Make an example with data based on the model from point $1.$ If necessary, modify your model for this example, providing arguments. Specify and define each basic relational operation performed to achieve the natural join.

And here's the translation:

Entity$/$Attribute Model:

Provide examples for each type$/$property and its variations on a small example of $3-4$ entities and attributes. Explain the concepts, their variations, properties of entities $($with several attributes$),$ and relationships between them for a database.

Explain the natural join $-$ entity, designations, properties. Make an example with data based on the model from point $1.$ If necessary, modify your model for this example, providing arguments. Specify and define each basic relational operation performed to achieve the natural join.