| 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 14801). This is not the
same as defining a specific function's mapping, which is typically done
using the format of cmpt 4729 with the maps-to notation (see df-mpt 4730 and
df-mpt2 6655). Contrast this predicate with the
predicates to determine
if some class is a function with a given domain (df-fn 5891), a function
with a given domain and codomain (df-f 5892), a one-to-one function
(df-f1 5893), an onto function (df-fo 5894), or a one-to-one onto function
(df-f1o 5895). For alternate definitions, see dffun2 5898, dffun3 5899,
dffun4 5900, dffun5 5901, dffun6 5903, dffun7 5915, dffun8 5916, and dffun9 5917.
(Contributed by NM, 1-Aug-1994.) |
