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 15632). This is not the
same as defining a specific function's mapping, which is typically done
using the format of cmpt 5135 with the maps-to notation (see df-mpt 5136 and
df-mpo 7218). Contrast this predicate with the
predicates to determine if
some class is a function with a given domain (df-fn 6383), a function
with a given domain and codomain (df-f 6384), a one-to-one function
(df-f1 6385), an onto function (df-fo 6386), or a one-to-one onto function
(df-f1o 6387). For alternate definitions, see dffun2 6390, dffun3 6391,
dffun4 6392, dffun5 6393, dffun6 6395, dffun7 6407, dffun8 6408, and dffun9 6409.
(Contributed by NM, 1-Aug-1994.) |