*80. ELEMENTARY PROPERTIES OF SELECTIONS.
Project Gutenberg EPUB3 edition
Whitehead, Alfred North and Russell, Bertrand
80·9·91 can be extended, by precisely similar proofs, to any finite number of variables , , .... They will, on occasion, be assumed for three or four variables, without fresh proofs.
*80·92.
Dem.
*80·93.
*80·94.
From this proposition, together with *80·26 (which gives , we shall obtain an inductive proof that exists whenever is a finite class contained in (cf. *120·611).