Description: Define predicate that
determines if some class 𝐴 is a function.
Definition 10.1 of [Quine] p. 65. For
example, the expression
Fun cos is true once we define cosine (df-cos 15414). This is not the
same as defining a specific function's mapping, which is typically done
using the format of cmpt 5138 with the maps-to notation (see df-mpt 5139 and
df-mpo 7150). Contrast this predicate with the
predicates to determine if
some class is a function with a given domain (df-fn 6352), a function
with a given domain and codomain (df-f 6353), a one-to-one function
(df-f1 6354), an onto function (df-fo 6355), or a one-to-one onto function
(df-f1o 6356). For alternate definitions, see dffun2 6359, dffun3 6360,
dffun4 6361, dffun5 6362, dffun6 6364, dffun7 6376, dffun8 6377, and dffun9 6378.
(Contributed by NM, 1-Aug-1994.) |