**READING: I §3 1**
Back to reading**:**
I §2 7

*begin quote ita***"**

*CHAPTER I* [:]
**
Notions from Set Theory
**

These pages assume that the reader has the book and is reading along. topic index contents

Please read these notes from the beginning to here, and then paragraph 1 of §3.

*
begin quote
ita-1-3-1-pg8
*
**"**

If *X* and *Y* are sets, by a *function from X to Y* [...] is meant a rule which associates with each element of *X* a definite element of *Y*.

**"***end quote*

In particular, looking forward to chapter two on the real number system, I believe ...

*
begin quote
ita-1-3-1-pg8
*
**"**

[...] the essential thing is that given any [ANY] element of *X* there is associated, somehow, some definite element [ONE AND ONLY ONE ELEMENT] of *Y*.

**"***end quote*