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
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.
I will use this definition in the next paragraph.