Main Definitions
If A is an infinite set of regular cardinals, D is an ultrafilter on A, then we let denote the cofinality of the ordered set of functions where the ordering is defined as follows. if . pcf(A) is the set of cofinalities that occur if we consider all ultrafilters on A, that is,
Read more about this topic: PCF Theory
Famous quotes containing the words main and/or definitions:
“The main business of religions is to purify, control, and restrain that excessive and exclusive taste for well-being which men acquire in times of equality.”
—Alexis de Tocqueville (1805–1859)
“What I do not like about our definitions of genius is that there is in them nothing of the day of judgment, nothing of resounding through eternity and nothing of the footsteps of the Almighty.”
—G.C. (Georg Christoph)