Skip to main content
typo in LaTeX code
Source Link
Victor Dods
  • 643
  • 4
  • 12

Most, if not all, of the notions of derivative that I have so far seen have the property that they are locally defined -- meaning that the derivative of a map-type object at a point depends on the map only in an arbitrarily small neighborhood of said point.

One could define some sort of non-local "differential" operator in real analysis for example by convolving a derivative with a function having non-trivial support. I use quotes here, because the operator involves integration as well as differentiation.

A less explicit but more apropos example would be an operator $N$ taking a manifold morphism $phi$$\phi$ to a vector bundle morphism $N\phi$, but which does not respect the restriction and gluing concepts used in sheaf theory (which I understand to be an abstract way to say that something is locally defined). The tangent map operator on manifold morphisms is a similar type of object, except that it can be shown to be locally defined. Thus $N\phi$ would "taste" like a derivative in that it has the same form as $T\phi$, but is not locally defined.

  1. Could an operator such as $N$ qualify as a differential operator (equivalently, would $N\phi$ qualify as a derivative of $\phi$)?
  2. Generally, what is the essential quality defining a "derivative"? My guess is that an answer would live in the realm of sheaf theory.

Most, if not all, of the notions of derivative that I have so far seen have the property that they are locally defined -- meaning that the derivative of a map-type object at a point depends on the map only in an arbitrarily small neighborhood of said point.

One could define some sort of non-local "differential" operator in real analysis for example by convolving a derivative with a function having non-trivial support. I use quotes here, because the operator involves integration as well as differentiation.

A less explicit but more apropos example would be an operator $N$ taking a manifold morphism $phi$ to a vector bundle morphism $N\phi$, but which does not respect the restriction and gluing concepts used in sheaf theory (which I understand to be an abstract way to say that something is locally defined). The tangent map operator on manifold morphisms is a similar type of object, except that it can be shown to be locally defined. Thus $N\phi$ would "taste" like a derivative in that it has the same form as $T\phi$, but is not locally defined.

  1. Could an operator such as $N$ qualify as a differential operator (equivalently, would $N\phi$ qualify as a derivative of $\phi$)?
  2. Generally, what is the essential quality defining a "derivative"? My guess is that an answer would live in the realm of sheaf theory.

Most, if not all, of the notions of derivative that I have so far seen have the property that they are locally defined -- meaning that the derivative of a map-type object at a point depends on the map only in an arbitrarily small neighborhood of said point.

One could define some sort of non-local "differential" operator in real analysis for example by convolving a derivative with a function having non-trivial support. I use quotes here, because the operator involves integration as well as differentiation.

A less explicit but more apropos example would be an operator $N$ taking a manifold morphism $\phi$ to a vector bundle morphism $N\phi$, but which does not respect the restriction and gluing concepts used in sheaf theory (which I understand to be an abstract way to say that something is locally defined). The tangent map operator on manifold morphisms is a similar type of object, except that it can be shown to be locally defined. Thus $N\phi$ would "taste" like a derivative in that it has the same form as $T\phi$, but is not locally defined.

  1. Could an operator such as $N$ qualify as a differential operator (equivalently, would $N\phi$ qualify as a derivative of $\phi$)?
  2. Generally, what is the essential quality defining a "derivative"? My guess is that an answer would live in the realm of sheaf theory.
Source Link
Victor Dods
  • 643
  • 4
  • 12

What essential property justifies the name "derivative"?

Most, if not all, of the notions of derivative that I have so far seen have the property that they are locally defined -- meaning that the derivative of a map-type object at a point depends on the map only in an arbitrarily small neighborhood of said point.

One could define some sort of non-local "differential" operator in real analysis for example by convolving a derivative with a function having non-trivial support. I use quotes here, because the operator involves integration as well as differentiation.

A less explicit but more apropos example would be an operator $N$ taking a manifold morphism $phi$ to a vector bundle morphism $N\phi$, but which does not respect the restriction and gluing concepts used in sheaf theory (which I understand to be an abstract way to say that something is locally defined). The tangent map operator on manifold morphisms is a similar type of object, except that it can be shown to be locally defined. Thus $N\phi$ would "taste" like a derivative in that it has the same form as $T\phi$, but is not locally defined.

  1. Could an operator such as $N$ qualify as a differential operator (equivalently, would $N\phi$ qualify as a derivative of $\phi$)?
  2. Generally, what is the essential quality defining a "derivative"? My guess is that an answer would live in the realm of sheaf theory.