Colleagues, I am planning to change this thread to a category.
However, at the moment, I will post my second communication of the thread CMT.
Let us define another differential operator of infinite terms as :
e^{-D}:=∑_{j=0}^{∞}(((-1)^{j}D^{(j)})/(j!))
when j=0, we have the identity operator, and D:=(d/(dx))
Then as in my first communication post, we can question the following:
(∀ψεC^{∞}(I,ℝ))Λ(∀xεI), what will be
e^{-D}(ψ(x))=∑_{j=0}^{∞}(((-1)^{j}D^{(j)}ψ(x))/(j!))?
Consider the following example:
Example 1: Take ψ(x)=e^(x) the usual natural exponential function.
Claim: e^{-D}(ψ(x))=ψ(x-1)
Indeed,
e^{-D}(ψ(x))=∑_{j=0}^{∞}(((-1)^{j}D^{(j)}ψ(x))/(j!))
=∑_{j=0}^{∞}(((-1)^{j}D^{(j)}(e^{x}))/(j!))
=∑_{j=0}^{∞}(((-1)^{j}e^{x})/(j!))
=e^(x)∑_{j=0}^{∞}(((-1)^{j})/(j!))
=e^(x-1)=ψ(x-1)
∴ e^{-D}ψ(x)=ψ(x-1) ... which is a right translation of ψ by a unit.
One can extend this result further and write a corollary as :
Corollary: (∀kεℕ):(e^{-D})^{k}ψ(x)=ψ(x-k)-right translate of ψ by k-units.
Example 2. Let φ(x)=x³+x²+x+1.Then
e^{-D}φ(x)=∑_{j=0}^{∞}(((-1)^{j}D^{(j)}φ(x))/(j!))
=∑_{j=0}^{∞}(((-1)^{j}D^{(j)}(x³+x²+x+1))/(j!))
=x³-2x²+2x
But the expression we have at the end is precisely φ(x-1).
That is, once again we have a similar result :
e^{-D}φ(x)=φ(x-1)
Corollary: ∀ p(x) , e^{-D}p(x)=p(x-1)
Conjecture: ∀ψεC^{∞}(I,ℝ), e^{-D}ψ(x)=ψ(x-1)
Corollary to the conjecture: (∀kεℕ)(∀ψεC^{∞}(I,ℝ)),e^{-kD}ψ(x)=ψ(x-k)
Further communications will be posted on operators defined from combinations of both.