# [FOM] R: A historical question about notation

iao271055 at libero.it iao271055 at libero.it
Thu Aug 22 05:09:01 EDT 2013

```Dear Thomas Forster,

Russell's notation originates mainly from Peano. If you have a look at G.
Peano, 'The principles of arithmetic, presented by a new method', especially
sections II and IV, in: J. van Heijenoort (ed:), 'From Frege to Goedel',
Harvard University Press, 1967, pp. 83-97, I am confident you will find the
answer to your questions. One very important thing to keep in mind for
questions about notation is that Peano wrote the book in latin, its original
title being: Arithmetices principia.

Best wishes,

Gianluigi Oliveri

>----Messaggio originale----
>Da: T.Forster at dpmms.cam.ac.uk
>Data: 20-ago-2013 5.57
>A: <fom at cs.nyu.edu>, <aphazen at ualberta.ca>
>Cc: <P.Bursill-Hall at dpmms.cam.ac.uk>
>Ogg: [FOM] A historical question about notation
>
>Over lunch today with one of the members of this list, the question of the
>notation for the empty set came up. I am wondering if listmembers can
>confirm the following allegations which i find floating around inside my
>
>1   The capital \$\Lambda\$ notation for the empty set (used by Russell and
>    Quine) is a capital `L' connoting German `leer';
>
>2   The `v' for disjunction comes from Latin `vel' meaning `or';
>
>3   `\$\cup\$' for set union derives from vel;
>
>4 `\$\cap\$' derives from `\$\cup\$' and `\$\wedge\$' analogously from `\$\vee\$' -
>    turning symbols upside-down connotes duality.
>
>5   `\$V\$' for the universe is an upside-down `\$\Lambda\$'.
>
>I'm pretty sure about (2) but not at all confident about some of the
>others.
>
>
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```