What are sets, matrices, …etc?

Question

I am writing a CS research paper where I'm using sets, matrices, and vectors to solve a particular problem. I have two sets, $R$ and $T$, that will be used throughout the entire solution, and a couple of other sets and matrices that won't be used much, so, I wanted to define $R$ and $T$ before writing the approach. Here is what I said:

$\dots\text{we will define some basic structures that will be used}\dots$

And I think $\text{“basic structures”}$ is wrong, so my question is what do I call (how do I refer to) sets, matrices, vectors, ...etc? How do I say what I want to say?

Answer 1

In fact, “structures” is a bad option. I think that “entities” is a much better choice.

Answer 2

"We begin by establishing some notation that will be used below. $R=\dots$, $S=\dots$"