Finite Definition and 1000 Threads

Is there a finite model of ZF - Infinity?

If you were to describe a line segment as the set where all of its infinite points were individual elements within the set than wouldn't the overall set which is the line segment also be considered infinite and not finite.

I need to construct a finite series with N elements, such that: element 1 has the value A element N has the value B elements 1 through N sum to Z A, B and Z are all positive numbers, as is Z. Additionally, I would like minimize the largest difference between any adjacent numbers in the...

Dear all, i met a problem that i couldn't get the on axis field of a finite solenoid that integrating from a thin shell solenoid equation. The thin shell equation link: http://www.netdenizen.com/emagnet/solenoids/thinsolenoid.htm And the on axis finite solenoid equation link...

Ok so I finished the 2nd year of my physics degree in july and have been looking at some of my notes so I don't forget everything before I start again but it struck me that I still don't understand square wells for quantum particles all too well. I understand how for ψ(x) behaves inside and...

If i know that Pr(X_t>b)=0, where X_t>0 and b is positive finite, then should the expectation of X_t be finite? Is there any case where it is infinite?

http://img22.imageshack.us/img22/1958/physicsl.jpg My attempt, After all the integrals I've got the final equation (1/4piE0) * |q| / ( d * sqrt ( d^2 + (L/2)^2) ) i'm not too sure how to express it how the question asks, please help! the bit I'm confused on, is the ( d * sqrt (...

Prove that if X and Y have finite second moments (i.e. E(X^2) and E(Y^2) are finite), then X+Y has a finite second moment. (X+Y)^2 ≤ X^2 + Y^2 + 2|XY| => E[(X+Y)^2] ≤ E(X^2) + E(Y^2) + 2E(|XY|) I don't understand the (probably incomplete) proof. On the right side, E(X^2) and E(Y^2) are...

I have attempted to find solutions for this netwide and can't find one that actually satisfies my questions so I am asking here. I am returning to school at the age of 32 and am trying to pre-learn some material before jumping back into the physics classes I need. A lot of the concepts are fuzzy...

Hi all I have a question regarding Bloch's theorem (also known as Floquet's theorem) and its use. I have seen in many solid state textbooks the famous problem of N coupled oscillators where one finds the dispersion relation analytically by using Bloch's theorem. However many times, authors...

Hello everybody! I am trying to construct the FDFD method for 3D structures. I have already constructed the general formulation and specifically I have set the complete matrix form. Due to the fact that the matrices are too sparse, and my system is out of memory, I am trying to set the problem...

1. 1. Find the exact(no approximations)sum for the finite series S sub n= (2 + 2 + 2(2+...+64 i used the parentheses to represent a radical sign 2. Show that the sum of the first 10 terms of the geometric series 1 + 1/3 + 1/9 + 1/27+... is twice the sum of the first 10 terms of...

Could someone provide a reference to calculate this kind of integrals ? for example \int_{0}^{2}dx \frac{cos(x)}{x-1} or in 3-D \iiint_{D}dx \frac{x-y+z^{2})}{x+y+z} Where 'D' is the cube [-1,1]x[-1,1]x[-1,1]=D as you can see there is a singularity at x=1 or whenever x+y+z=0 ...

F3 is a finite field with 3 elements and V is a vector space of n-tuples of elements from F3. Is there a way to calculate the maximum number of elements in a subset S of V, such that for no three elements a,b,c in S a+b+c=0? Or in other words, no three elements in S are on the same line...

Hi, I haven't found special topic about cosmology on this site so I hope this cathegory fits the best. The questions are: 1) Is cosmos(universe) finite or infinite? According to some articles I have read about inflation it seems that inflation theory works only with finite number of particles...

Hello I have an assignemt to analysis a landing gear for the cyclone earoplane, an initial design being supplied, I have being askedto check for the suitability of the part, the conditions are: Aircraft mass with fuel: 43000 lbs Landing speed: 65 Knots Maximum deceleration: 3g Each part...

Hi, I am in the process of learning QM. I am looking at this problem regarding to a finite square potential well. I have derived psi(x) and the k's for the 3 domains, psi1(x) = Ae^kx => k = sqrt(2m(V-E)/h^2) psi2(x) = Ce^jkx + De^-jkx => k=sqrt(2mE)/h psi3(x) = He^-kx => same k...

Homework Statement Let F be a field, and suppose that alpha is algebraic over F. Prove that if [F(alpha):F] is odd, then F(a^2)=F(a). {For those unfamiliar with notation [] denotes degree of extension and F(alpha) means F adjoined with alpha.) The Attempt at a Solution Since [F(alpha):F]...

Homework Statement Count and describe the different isomorphism classes of abelian groups of order 1800. I don't need to list the group individually, but I need to give some sort of justification.Homework Equations The Attempt at a Solution I'm using the theorem to classify finitely generated...

Hi I am trying to solve a nonlinear differential equation with the use of the finite difference method and the Newton-Raphson method. Is there anyone that knows where I can find some literature about the subject? I am familiar with the use of the finite difference method, when solving...

I have a problem with this one question that is driving me crazy. It seems so simple. I have done definite integrals, 'U' substitutions, and integration by parts, etc, etc... Anyway, here's the question, maybe you guys can help me out. This isn't a homework question or anything, it just has been...

Homework Statement Let H be a finite abelian group that has one subgroup of order d for every positive divisor d of the order of H. Prove that H is cyclicHomework Equations We want to show H={a^n|n is an integer}

Homework Statement An abelian group has order pn (where p is a prime) and contains p-1 elements of order p. Prove that this group is cyclic. Homework Equations The Attempt at a Solution I know I should use the theorem for classifying finite abelian groups, which I understand, and...

Hi The equation is: \frac{dP}{dt}-A*\frac{{d}^2P}{dx^2}-B*\frac{dC}{dt}=0 dP/dt=A*d2P/dx^2 was solved using a finite difference method. If the function C(x,t) is known, is it possible to solve the whole equation by using the finite difference solution as a supplement to the complete solution...

Homework Statement Let G be a finite group and let p >= 3 be a prime such that p | |G|. Prove that the group ring ZpG is not a domain. Hint: Think about the value of (g − 1)p in ZpG where g in G and where 1 = e in G is the identity element of G. The Attempt at a Solution G is a...

I know that the basis is finite set of vectors that are linearly independant and SPANS that set. But why is when you find the basis for the row space for example the answer is {[u1,u2,...,um}} and not span{[u1,u2,...,um}]. I got this wrong in a test. I don't see why eventhough the definition...

The essay question I have chosen for my assignment is the following: " If you are traveling in a car at the speed of light and you turn on your headlamps, will the light emitted illuminate the path in front of you?" I am not concerned with the car or its occupants in any...

I am trying to prove that if c is a root of f(x) in Z_p then c^p is also a root. It seems very simple but I can't think how to approach it. Any insight on this would be greatly appreciated, and sorry for not using the latex but it seems to be acting up.

Hi I am trying to solve the Poisson equation, with the use of the Finite Difference Method, for a inhomogeneous media with some charge distributions embedded in the media. Is there anyone that know some literature, which treats this subject? Thanks in advance

I need to convert a 2D code to 1D for a simply supported beam using matlab. Does anyone have any experience regarding to this?

Homework Statement 1) The probability density at certain points for a particle in a box is zero. Does this imply that the particle cannot move across these points? There was also 2 figures that go with it, but I don't know if it's possible to upload them. One shows psi against the length of...

Homework Statement Let G be a finite group andd H a subset of G. Prove H is a subgroup of G iff H is closed. Homework Equations The Attempt at a Solution Let G be a finite group and H be a subgroup. G is a finite group, therefore it is closed, has an inverse and has an identity...

Hi, Does anyone know where I can get any programming for finite element in 3d object not calculation but for the display such as cad (e.g. meshing display)? Also what software that can do above operation? I mean, not ansys, nastran, algor, etc., but other that I can make it by myself by my...

Is every first order theory with finitely many axioms automatically complete? An axiom schema like that of ZFC's separation counts as an infinite number of axioms.

I'm going to take a finite difference linear and non-linear PDE course next semester. I'm wondering how enjoyable the material is, and how difficult it may be. I'm actually looking forward to the fact there may only be one test throughout the semester, if any, and it's a mid-term. The rest of...

Suppose we have two finite abelian groups G,G^{\prime} of size n=pq, p,q being primes. G is cyclic. Both G,G^{\prime} have subgroups H,H^{\prime}, both of size q. The factor groups G/H,\ G^{\prime}/H^{\prime} are cyclic and since they are of equal size, they are isomorphic. Are G,G^{\prime}...

Homework Statement From Hoel, Port, & Stone, Chapter 4, Exercise 9: Construct an example of a density that has a finite moment of order r but has no higher finite moment. Hint: Consider the series \sum_{k=1}^{\infty} k^{-(r+2)} and make this into a density. Btw, this is for my own...

This is more a qualitative question than a specific homework question, but a homework problem got me wondering about it. I was solving the finite potential well. V(r) = 0 \hspace{1cm} r \geq a V(r) = -V_0\hspace{1cm} r < a I am trying to solve for the ground state energy. When I find...

Homework Statement The figure shows a thin rod of length L and charge Q. It lies directly along the x-axis with its center at the origin. Find an expression for the electric potential a distance x away from the center of the rod on the axis of the rod. (Give your answer in terms of x, L, Q and...

Let O(n,F_q) be the orthogonal group over finite field F_q. The question is how to calculate the order of the group. The answer is given in http://en.wikipedia.org/wiki/Orthogonal_group#Over_finite_fields". This seems to be a standard result, but I could not find a proof for this in the basic...

Homework Statement A beam of electrons of KE = 100 eV is incident from the left on a barrier which is 200 eV high and 10 nm wide. If the momentum spread is sufficiently narrow, then a simple plane wave is a good approximation. Recall that the mass of an electron is mc2 = 511 keV. ....._____...

Homework Statement Suppose that m = 1 mod b. What integer between 1 and m-1 is equal to b^(-1) mod m? The Attempt at a Solution m = 1 mod b means that: m = kb + 1 for some integer k Let x be the inverse of b mod m, note: x exists since b and m must be coprime due to the previous...

Energy signal? hai.. i want to know why is energy signal having a finite energy value and 'zero value of power' similarly the power signal have finite value of power and an INFINITE VALUE OF ENERGY

I have read that "A universe with a spherical geometry is called a closed universe because a universe with this geometry must be finite" but even after looking up different sources i cannot find an decent explanation of it is finite. I know that a flat universe is just an unbound 3d grid that...

Paradox? An infinite set having finite volume?? Homework Statement Find the volume, in terms of k, of the solid made from R rotating about the y-axis, if R is defined as the region bounded by e^{-x} and the coordinate axes. 2. The attempt at a solution Obviously, \displaystyle\int^{1}_{0}...

I'm guessing there has been an attempt to address this, and I've looked through some threads but I remain unsatisfied. I'm not getting it. If relativity predicts that the universe was a singularity (I get that the universe wasn't necessarily a tiny point) with infinite density; then how could...

Let x^2_1+x^2_2=1 be an unit circle upon a finite field Z_{p} where p is a prime. Is there any algorithm (other than the brute force algorithm) which can give all the possible solutions (x_1,x_2)\in Z_{p}\times Z_{p} as well as the total number of such solutions? If exists, what is the...

Hello I have a question if anyone know the answer I appreiatete it, the question is that when doing FEM for a frame in just 4 elements is more correct to solve it by using stiffness matrix and spread sheets or by using ProE is more correct answer can be found, please can you explain it for me...

Homework Statement Determine the transmission coefficient for a rectangular barrier. Treat seperately the three cases E<Vo, E>Vo, and E=Vo.Homework Equations V(x)= +Vo if -a<xa V(x)= 0 otherwise Transmission coefficient=(amplitude of transmited wave)2/(amplitude of incoming wave)2 I am also...

Symmetry Arguments--a finite cylindrical can Homework Statement Consider a finite cylindrical can shape that has charge uniformly distributed on its surface. Symmetry does allow us to say some things about the electric field of this distribution A) at points along the can's central axis B) At...