READING:     I     3     5                    Back to reading:     I     3     4
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 5 of 3.

GENERAL DEFINITION OF FUNCTIONS

begin quote ita-1-3-5-pg9 "
It is useful to note that the word "function" alone can be defined in primitive terms, not only the more complete concept "function from   X   into   Y ": a function is an ordered pair whose first member is an ordered pair of sets, say   ( X,Y )   and whose second member is a function from   X   into   Y.
"end quote

I will use this definition in the next paragraph.

on to reading 6