Integrals sum over infinitely small values. Is it possible to multiply infinitely small factors? For example, Integration of some random dx is a constant, since infinitely many infinitely small values can sum up to any constant. But can you do something along the lines of taking an infinitely large root of a constant, and get an infinitesimal differential in that way? Multiplying those differentials will yield some constant again.
My off the cuff impression is that this probably won’t lead to genuinely new math. In the most basic case, all it does is move the integrations into the powers that other stuff is raised by. But if we somehow end up with complicated patterns of logarithms and exponentiations, like if that other stuff itself involves calculus and so on, then who knows? Is there a standard name for this operation?
What is the analogy of sum that you’re thinking about? Ignoring how the little pieces are defined, what would be a cool way to combine them? For example, you can take the product of a series of numbers to get any number, that’s pretty cool. And then you can convert a series to a continuous function by taking a limit, just like an integral, except rather than the limit going to really small pieces, the limit goes to pieces really close to 1.
You could also raise a base to a series of powers to get any number, then take that to a continuous limit to get an integral-analogue. Or do other operations in series, but I can’t think of any really motivating ones right now.
Can you invert these to get derivative-analogues (wiki page)? For the product integral, the value of the corresponding derivative turns out to be the limit of more and more extreme inverse roots, as you bring the ratio of two points close to 1.
Are there any other interesting derivative-analogues? What if you took the inverse of the difference between points, but then took a larger and larger root? Hmm… You’d get something that was 1 almost everywhere for nice functions, except where the function’s slope got super-polynomially flat or super-polynomially steep.
Someone has probably thought of this already, but if we defined an integration analogue where larger and larger logarithmic sums cause their exponentiated, etc. value to approach 1 rather than infinity, then we could use it to define a really cool account of logical metaphysics: Each possible state of affairs has an infinitesimal probability, there are infinitely many of them, and their probabilities sum to 1. This probably won’t be exhaustive in some absolute sense, since no formal system is both consistent and complete, but if we define states of affairs as formulas in some consistent language, then why not? We can then assign various differential formulas to different classes of states of affairs.
(That is the context in which this came up. The specific situation is more technically convoluted.)
Thanks, product integral is what I was talking about. The exponentiated integral is what I meant when I said the integration will move into the power term.
No, he’s right. I didn’t think to clarify that my infinitely small factors are infinitesimally larger than 1, not 0. See the Type II product integral formula on Wikipedia that uses 1 + f(x).dx.
I am afraid, that multiplication of even countably many small numbers yields 0. Let alone the product of more than that, what your integration analogous operation would be,
You can get a nonzero product if the sum of differences between 1 and your factors converge. Then and only then. But if all the factors are smaller than say 0.9 … you get 0.
Except if you can find some creative way to that anyway. Might be possible, I don’t know.
Yeah, it might have helped to clarify that the infinitesimal factors I had in mind are not infinitely small as numbers from the standpoint of addition. Since the factor that makes no change to the product is 1 rather than 0, “infinitely small” factors must be infinitesimally greater than 1, not 0. In particular, I was talking about a Type II product integral with the formula pi(1 + f(x).dx). If f(x) = 1, then we get e^sigma(1.dx) = e^constant = constant, right?
Integrals sum over infinitely small values. Is it possible to multiply infinitely small factors? For example, Integration of some random dx is a constant, since infinitely many infinitely small values can sum up to any constant. But can you do something along the lines of taking an infinitely large root of a constant, and get an infinitesimal differential in that way? Multiplying those differentials will yield some constant again.
My off the cuff impression is that this probably won’t lead to genuinely new math. In the most basic case, all it does is move the integrations into the powers that other stuff is raised by. But if we somehow end up with complicated patterns of logarithms and exponentiations, like if that other stuff itself involves calculus and so on, then who knows? Is there a standard name for this operation?
What is the analogy of sum that you’re thinking about? Ignoring how the little pieces are defined, what would be a cool way to combine them? For example, you can take the product of a series of numbers to get any number, that’s pretty cool. And then you can convert a series to a continuous function by taking a limit, just like an integral, except rather than the limit going to really small pieces, the limit goes to pieces really close to 1.
You could also raise a base to a series of powers to get any number, then take that to a continuous limit to get an integral-analogue. Or do other operations in series, but I can’t think of any really motivating ones right now.
Can you invert these to get derivative-analogues (wiki page)? For the product integral, the value of the corresponding derivative turns out to be the limit of more and more extreme inverse roots, as you bring the ratio of two points close to 1.
Are there any other interesting derivative-analogues? What if you took the inverse of the difference between points, but then took a larger and larger root? Hmm… You’d get something that was 1 almost everywhere for nice functions, except where the function’s slope got super-polynomially flat or super-polynomially steep.
Someone has probably thought of this already, but if we defined an integration analogue where larger and larger logarithmic sums cause their exponentiated, etc. value to approach 1 rather than infinity, then we could use it to define a really cool account of logical metaphysics: Each possible state of affairs has an infinitesimal probability, there are infinitely many of them, and their probabilities sum to 1. This probably won’t be exhaustive in some absolute sense, since no formal system is both consistent and complete, but if we define states of affairs as formulas in some consistent language, then why not? We can then assign various differential formulas to different classes of states of affairs.
(That is the context in which this came up. The specific situation is more technically convoluted.)
Good question!
The answer is called a Product integral. You basically just use the property
to turn your product integral into a normal integral
Thanks, product integral is what I was talking about. The exponentiated integral is what I meant when I said the integration will move into the power term.
I think that was not his question. Hi didn’t ask about product integral of f(x), but “product integral of x”.
EDIT: And that for “small x”. At least I understood his question so.
No, he’s right. I didn’t think to clarify that my infinitely small factors are infinitesimally larger than 1, not 0. See the Type II product integral formula on Wikipedia that uses 1 + f(x).dx.
Sum : integral of f(x) :: product :: exp(integral of log(f(x)))
I am afraid, that multiplication of even countably many small numbers yields 0. Let alone the product of more than that, what your integration analogous operation would be,
You can get a nonzero product if the sum of differences between 1 and your factors converge. Then and only then. But if all the factors are smaller than say 0.9 … you get 0.
Except if you can find some creative way to that anyway. Might be possible, I don’t know.
Yeah, it might have helped to clarify that the infinitesimal factors I had in mind are not infinitely small as numbers from the standpoint of addition. Since the factor that makes no change to the product is 1 rather than 0, “infinitely small” factors must be infinitesimally greater than 1, not 0. In particular, I was talking about a Type II product integral with the formula pi(1 + f(x).dx). If f(x) = 1, then we get e^sigma(1.dx) = e^constant = constant, right?
Right. There around 1 you often can actually multiply an infinite number of factors and get some finite result.