| Description: Multiplication is an
operation on the complex numbers.  This axiom tells
     us that · is defined only on complex
numbers which is analogous to
     the way that other operations are defined, for example see subf 8228
or
     eff 11828.  However, while Metamath can handle this
axiom, if we wish to work
     with weaker complex number axioms, we can avoid it by using the less
     specific mulcl 8006.  Note that uses of ax-mulf 8002 can be eliminated by using
     the defined operation (𝑥 ∈ ℂ, 𝑦 ∈ ℂ ↦ (𝑥 · 𝑦)) in place of
     ·, as seen in mpomulf 8016.
 
     This axiom is justified by Theorem axmulf 7936.  (New usage is discouraged.)
     (Contributed by NM, 19-Oct-2004.)  |