READING: I §3 1
Back to reading:
I §2 7
begin quote ita"
CHAPTER I [:] Notions from Set Theory [...] §3. FUNCTIONS. "end quote
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.
DESCRIPTION OF FUNCTIONS
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.
In particular, looking forward to chapter two on the real number system, I believe ...
[...] 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.