FOOTNOTES:
Project Gutenberg EPUB3 edition
Whitehead, Alfred North and Russell, Bertrand
Source notes
[1] Cf. Chapter II of the Introduction.
[2] This phrase is due to Frege.
[3] The meaning of these expressions will be explained later, and examples of the use of dots in connection with them will be given on pp. 17, 18.
[4] This case will be fully considered in Chapter III of the Introduction. It need not further concern us at present.
[5] This agrees with the rules for the occurrences of dots of the type of Group II as explained above, pp. 9 and 10.
[6] A value of is said to satisfy or when is true for that value of .
[7] Any other letter may be used instead of .
[8] Such a couple has a sense, i.e. the couple is different from the couple , unless . We shall call it a "couple with sense," to distinguish it from the class consisting of and . It may also be called an ordered couple.
[9] The same principle applies to many uses of the proper names of existent objects, e.g. to all uses of proper names for objects known to the speaker only by report, and not by personal acquaintance.
[10] The second of these notations is taken from Schröder's Algebra und Logik der Relative.
[11] This relation is not strictly asymmetrical, but is so except when the wife's brother is also the sister's husband. In the Greek Church the relation is strictly asymmetrical.