Abstract

On p. 261 of MIND, No. 146 (April, 1928), the relation expressed by the words “is a itbfamily of” would be better expressed by some other phrase such as “is a subsystem of”. For the notion which I defined at the end of the note was, through a stupid mistake on my part, incorrectly described as “a family,” whereas really it should hare received some quite distinct designation such as “a maximal system”. The term “family” should of course be used in the sense which the authors of Principia Mathematica.have assigned to it And this sense only coincides with the sense of “ maximal system ” in the special case where R is a one-one relation ; in other cases more than one family may be included in a single maximal system On it. 260 two small corrections are required. For “ Rbo ” read “ Rpo ”. And the footnote should have had the number “ 1 ” prefixed to it, making it clear that it is a footnote and refers to section (3), and is not a continuation of section (4)