Spiderman and the Cantor's function .

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Well it's an imaginative and soft question so take it as you wish .

Problem : imagine Spider-man walking on the cantor function (see the plot like the side of a building) :

cantor-function

Now he can throw a line to come faster to the top of the stairs . The problem is the spider-man webs can only solidify on an angle(i.e corner).

Question :

If spiderman have a limitied number of spider-webs which stay only on angle (corner) what is the probability he comes to the top of the stairs on a limited interval of the Cantor's function admitting it's his only means of transport ?

Do you have a strategy ?

I have no attempt because it's a new problem for me but Bernoulli's distribution could be a start .

Example of path to come on a horizontal line :

Spiderman-path

The new question is :

Finalizing Question :


If Spiderman is a point on that curve and have the probability $P=1/2$ to get a rational point $(x_i,y_i)$ on the curve he choose (The Cantor set here) and stop if the point is irrational what's the probability he goes at the top of the devil staircase ($x=y=1$) if he is assimilated to an increasing unknow $x$ starting to $x=0$ and $x_i<x_{i+1}$.In other word what's the probability he diverges (projective geometrical point of view) to $x=y=1$ choosing a number of rational point which is bounded ?

We can bound it with the Fréchet-Boole's inequality .

To figure it see :

Circle-ford

Another one and Thomae function

Popcornfunction

The problem can be reformulate in term of Brownian motion :

Spidermanmotion

Simplifying question for kids :

If now a kid plays with a Soap bubble and the bubble in a slight wind goes to a staircase what's chance the bubble don't collapse before the end of the next level of the home?

Reference :

https://en.m.wikipedia.org/wiki/Cantor_distribution

https://en.wikipedia.org/wiki/Fr%C3%A9chet_inequalities

https://en.wikipedia.org/wiki/Ford_circle

https://arxiv.org/pdf/2007.08407v1.pdf

https://arxiv.org/ftp/arxiv/papers/2205/2205.01925.pdf

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The basis of this answer and the strategy which come with it start :

What is the convex hull of the devil staircase taking only extremal point $P_i$ which is bounded ?

In fact if Spiderman (view as a point) have an illimited numbers of webs Jarvis march is sufficient if we admits there is a limited numbers of point in the convex hull .

Now as it's limited we can refine Jarvis march with Chan's algorithm which is more efficient .

There are other strategy but take it as an example for this problem of computational geometry .

Hope you find something clear and give your feedback.

Edit :

In term of probabilities see Expected number of vertices in a convex hull





From here (p.35) it seems that the probability is equal to $1/2$ is it right ?(false)

See https://people.maths.bris.ac.uk/~matmj/Demislides.pdf and Mahler question .

Using this paper the answer seems to be $P\simeq 1/3^n$ (false too)

I found an partial answer here Continued Fraction and Random Variable

And here "Probability" measures on Cantor set

Edit :

If we consider the term "equiprobable" so the answer is $1/2$ see

Thou shalt not say “at random” in vain: Bertrand’s paradox exposed



See theorem 5.1 Tchernoff bound here