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Full Idea
I define a 'symbol' (of the predicate calculus) as either a bracket or a logical connective or a term or an individual variable or a predicate-letter or reverse-E (∃).
Gist of Idea
The 'symbols' are bracket, connective, term, variable, predicate letter, reverse-E
Source
E.J. Lemmon (Beginning Logic [1965], 4.1)
Book Ref
Lemmon,E.J.: 'Beginning Logic' [Nelson 1979], p.139
13909 | Write '(∀x)(...)' to mean 'take any x: then...', and '(∃x)(...)' to mean 'there is an x such that....' [Lemmon] |
13902 | 'Gm' says m has property G, and 'Pmn' says m has relation P to n [Lemmon] |
13911 | The 'symbols' are bracket, connective, term, variable, predicate letter, reverse-E [Lemmon] |
18952 | '⊃' ('if...then') is used with the definition 'Px ⊃ Qx' is short for '¬(Px & ¬Qx)' [Putnam] |