The abelian sandpile model is a cellular automaton where each cell is a sandpile that can topple to put grains on neighboring cells when having enough grains. It is stable if none of the sandpiles can topple. A natural question to ask is whether it can become stable eventually. In this article, I will show that one can determine the stabilizibility usiung integer linear programming for the abelian sandpile model on an arbitrary finite graph.
Several features of the eigenfunctions of the Laplacian on an annulus with homogeneous Neumann boundary condition are discussed. The distribution of the eigenvalues is discussed in detail, making use of a phase angle function called θ. The limiting cases of a disk and a circle are discussed.
I was briefly introduced to Grassmann numbers when I studied quantum field theory. I then had the natural question of how we can formally define them. In this article, I went with my intuition and tried to answer this question.
For a plane lattice, there is only a finite number of different rotational symmetries that are compatible with the discrete translational symmetry. For example, the 5-fold rotational symmetry is not one of them. Why is that? It turns out that whether an m-fold symmetry is compatible with translational symmetry is the same as whether φ(m)≤2.
Suppose there are n distinguishable boxes and k indistinguishable balls. Now, we randomly put the balls into the boxes. For each of the boxes, what is the probability that it contains m balls? This is a simple combanitorics problem that can be solved by the stars and bars method. It turns out that in the limit n,k→∞ with k/n fixed, the distribution tends to be a geometric distribution.
Denote the length distribution of one’s hair to be f(l,t), where l is hair length, and t is time. Considering that each hair may be lost naturally from time to time (there is a probability of λdt for each hair to be lost within time range from t to t+dt) and then restart growing from zero length, how will the length distribution of hair evolve with time? It turns out that we may model it with a first-order PDE.
Given your probability of breaking the combo at each note, what is the probability distribution of your max combo in the rhythm game chart? I considered the problem seriously!
By recursively integrating according to xn+1(t):=∫t0tf(xn(s),s)ds+C from x0(t0):=C, we can get the solution of the ODE
x′(t)=f(x(t),t) with initial conditions x(t0)=C as the limit of the sequence of functions.
The Hölder mean of x with weights w and a parameter p is defined as Mp,w(x):=(w⋅xp)p1, and the value at p=−∞,0,+∞ are defined by the limits. We can prove using Jensen’s inquality that the Hölder mean increases as p increases. This property can be used to prove HM-GM-AM-QM inequalities.