Group Definition and 1000 Threads

  1. K

    B Matrices of su(3) and sphere symmetry

    i used to get pauli matrices by the following steps it uses the symmetry of a complex plane sphere i guess so..? however i can't get the 8 gell mann matrices please help ! method*: (x y) * (a b / c d ) = (x' y') use |x|^2 + |y|^2 = |x'|^2 + |y'|^2 and |x| = x * x(complex conjugate) this way...
  2. PsychonautQQ

    Calculating a pretty simple Galois Group

    Homework Statement Describe the structure of the Galois group for G(Q(c):Q) where c is a 14th primitive root of unity Homework EquationsThe Attempt at a Solution the minimal polynomial for c over Q is f(x)=x^6-x^5+x^4-x^3+x^2-x+1. Is the galois group isomorphic to Z*_14? Or maybe that's only...
  3. Evo

    News Mike Pence Accused of Voter Suppression in Indiana Raid

    Indiana officials are trying to block almost 45,000 black citizens from voting Seems the voter's rights group wants the Justice department to look into this and the local police want to leave it with the local county prosecutors they work with. Either way, Police spokesman Bursten said the...
  4. PsychonautQQ

    Isomorphism to certain Galois group and cyclic groups

    Homework Statement Let c be a pth root of unit where p is prime. Then the Galois group G(Q(c):Q) is isomorphic to Z_p*. Show that if there is some m that divides p-1, then there is an extension K of Q such that G(K:Q) is isomorphic to Z_q* Homework EquationsThe Attempt at a Solution I suspect...
  5. alexmahone

    MHB Is G an Abelian Group Given Specific Conditions?

    Let $G$ be a group such that for all $a$, $b$, $c$, $d$, and $y\in G$ if $ayb=cyd$ then $ab=cd$. Show that $G$ is an Abelian group. HINTS ONLY as this is an assignment problem.
  6. V

    Courses Does this group theory course look useful to a physicist?

    I'm in my 3rd year of a physics degree, with plans to study further in graduate school. I am currently enrolled in a group theory class, as I have heard it can be useful in many fields (particularly solid state physics, which I am interested in learning more about). However, so far all we have...
  7. L

    A Maurer–Cartan forms for a matrix group?

    I am very confused about that in some literature the Maurer Cartan forms for a matrix group is written as ##{\omega _g} = {g^{ - 1}}dg## what is ##dg## here? can anyone give an example explicitly? My best guess is ## dg = \left( {\begin{array}{*{20}{c}} {d{x^{11}}}& \ldots &{d{x^{1m}}}\\...
  8. A

    Organic chemistry- adding amine group to benzene

    Is it possible to do a Friedel-Crafts reaction on a benzene and get a substituent on the benzene ring from that, and then afterwards add an NH2 group ortho? I know you can't add NH2 first and then do Friedel-Crafts because anilines cannot undergo Friedel-Crafts. Please advice. Thanks in advance.
  9. N

    Group velocity and phase velocity

    Could you please explain the derivation of group velocity = dw/dk I read ut here https://en.m.wikipedia.org/wiki/Group_velocity Is it approximation, if so under what circumstances
  10. G

    I Space Group Duplicates: Is it Possible for Monoatomic Crystals?

    Hello, I was building some test crystal structures with VESTA software and I noticed when generating the POSCAR output files to be read by VASP that for a simple monoatomic basis such as in elemental silicon crystals some distinct space groups produce the same exact POSCAR files (i.e. same...
  11. J

    Particle Group Theory book for Undergraduates

    Hello, what are some good books to learn group theory for physicists at an undergraduate level? Is Zee's Group Theory in a Nutshell good? Thanks in advance
  12. B

    Is the Centralizer of an Element in a Free Group Nontrivial?

    Homework Statement Note: I did not get this problem from a textbook. Let denote the (nonabelian) free group on the generators , and let be arbitrary. My question is, does there exist a such that , besides (the identity); is such an equation in the free group possible? Obviously this...
  13. JuanC97

    I Dimension of the group O(n,R) - How to calc?

    Hi, I want to find the number of parameters needed to define an orthogonal transformation in Rn. As I suppose, this equals the dimension of the orthogonal group O(n,R) - but, correct me if I'm wrong. I haven't been able to figure out how to do this yet. If it helps, I know that an orthogonal...
  14. micromass

    Insights Groups and Geometry - Comments

    micromass submitted a new PF Insights post Groups and Geometry Continue reading the Original PF Insights Post.
  15. T

    Which Group 14 Elements Share the Most Similar Properties?

    Homework Statement The elements lead, silicon, germanium, tin and carbon all lie in the same group of the periodic table. Which of the following is true? A) Like carbon, all the elements are non-metalsB) Carbon is closer in properties to silicon than tin is to leadC) Tin is closer in...
  16. D

    Schools Online schools with video lectures & no group work?

    I'm looking for an online American college for a bachelor's degree, with video lectures, and no group work. What are my options? I have difficulty with reading. This kind of a college would work best for me.
  17. baby_1

    Linearly Chirped Fiber Bragg Grating group delay

    Homework Statement Here is my problem : I want to know where does group delay equation come form? Homework Equations As I checked reference 21 it only indicates The Attempt at a Solution I'm following how can I start and solve this problem
  18. AJPsi

    A Has This Mysterious Mathematical Group Been Identified in Physics Research?

    While investigating various aspects of generalised least action principles over the last several years I have come across an algebraic mathematical group that I am finding hard to classify but whose root vectors should relate to the standard model (no it is not E8 ! nor any exceptional group I...
  19. mertcan

    Learn Group Theory: Sources & Resources

    Hi, I saw that group theory is a significant asset for some physics, and math topics. I had some fundamental knowledge, but I am really keen on learning group theory deeply , so Is there a nice source( video links, books... whatever comes to your mind ) to leap further in this topic remarkably?
  20. T

    A On the renormalization group flow

    I'm currently studying the Landau-Wilson model for critical phenomena (Statistical Mechanics, Kerson Huang) where the renormalization group is a central object. In the end, the calculations lead to a set of coupled differential equations that describe the (metaphorical) evolution of the...
  21. D

    I Is that the definition of a lie group?

    I learned a lie group is a group which satisfied all the conditions of a diferentiable manifold. that is the real rigour definition or just a simplified one? thanks
  22. J

    What is the group refractive index for a monochromatic wave in a laser cavity?

    Homework Statement .[/B] I am attempting to determine the group refractive index of a laser cavity at it's resonance frequency. Homework Equations .[/B] \begin{align*} \frac{2\omega n L}{c} &= 2m\pi \end{align*} \begin{align*} n_g &= n + \omega \frac{dn}{d\omega} \end{align*} 3. The attempt...
  23. PsychonautQQ

    I Group Normalcy not transitive example?

    The normal subgroup of a normal subgroup need not be normal in the original group (normalcy is not transitive). Could somebody provide me with an example of where this is the case? Thanks :D
  24. G

    I About Lie group product ([itex]U(1)\times U(1)[/itex] ex.)

    I recently got confused about Lie group products. Say, I have a group U(1)\times U(1)'. Is this group reducible into two U(1)'s, i.e. possible to resepent with a matrix \rho(U(1)\times U(1)')=\rho_{1}(U(1))\oplus\rho_{1}(U(1)')=e^{i\theta_{1}}\oplus e^{i\theta_{2}}=\begin{pmatrix}e^{i\theta_{1}}...
  25. Erebus_Oneiros

    Physics Advice before joining PhD research group, -- personal problems

    Advice before joining PhD research group, if I have a personal problem with one of the group members? One more student from my cohort wants to join the same research group as me. We will be doing our research rotation together. He has an overbearing attitude and is insolent towards anyone...
  26. Amy B

    Ordering Carbonyl Group Wavenumbers in NMR

    Homework Statement I want to put these in order of increasing wavenumber for the absorptions of the carbonyl group in an nmr spectrum Homework EquationsThe Attempt at a Solution I know that the third one is the highest, the NH ketoamine is the lowest and last one is the second lowest but I'm...
  27. C

    Programs Is It Appropriate to Email a Research Group Leader Directly as an Applicant?

    I applied to an undergraduate program at a nearby national lab that is tailored for students in the region. I was advised by one of the program staff to contact a research group that I'm interested in working with to let them know that I'm in the applicant pool, and that I am interested in...
  28. RJLiberator

    Two conjugate elements of a group have the same order PROOF

    Homework Statement Let x and y be conjugate elements of a Group G. Prove that x^n = e if and only if y^n = e, hence x and y have the same order. Homework Equations Conjugate elements : http://mathworld.wolfram.com/ConjugateElement.html The Attempt at a Solution Since y is a conjugate of x...
  29. B

    Proving the Exponent Laws in Group Theory

    Homework Statement Let ##x \in G## and ##a,b \in \mathbb{Z}^+## Prove that ##x^{a+b} = x^a x^b##. Homework EquationsThe Attempt at a Solution If I am not mistaken, we would have to do multiple induction on ##a## and ##b## for the statement/proposition ##P(a,b) : x^{a+b} = x^a x^b##. First we...
  30. B

    Simple Verification of a Group

    Homework Statement Determine whether the set of rational numbers with denominator equal to 1 or 2 is a group under addition. Homework EquationsThe Attempt at a Solution Please have a look at the closure proof of part 5. I don't quite understand how ##q/2## implies that the denominator of...
  31. erbilsilik

    Research Orthogonal Lie Group for Physics Applications

    [Mentor's Note: Thread moved from homework forums] Where can I start to research this question? I did not take any course on Group theory before and I know almost nothing about the relationship with this pure maths and physics. I've decided to start with Arfken's book but I'm not sure. 1...
  32. matqkks

    I Group Theory: Unlocking Real-World Solutions for First-Year Students

    What is the most motivating way to introduce group theory to first year undergraduate students? I am looking for some real life motivation or something which has a real impact.
  33. matqkks

    MHB Group Theory: A Powerful Tool for Real World Solutions

    What is the most motivating way to introduce group theory to first year undergraduate students? I am looking for some real life motivation or something which has a real impact.
  34. S

    A Exceptional group and grand unified theory

    Dear All I have a project about exceptional group as a candidate group for grand unified theories. Can anyone suggest me any paper or reference to use. Thank you
  35. J

    I Commutator between Casimirs and generators for Lorentz group

    The generators ##\{ L^1, L^2 , L^3 , K^1 , K^2 , K^3 \}## of the Lorentz group satisfy the Lie algebra: \begin{array}{l} [L^i , L^j] = \epsilon^{ij}_{\;\; k} L^k \\ [L^i , K^j] = \epsilon^{ij}_{\;\; k} K^k \\ [K^i , K^j] = \epsilon^{ij}_{\;\; k} L^k \end{array} It has the Casimirs C_1 =...
  36. M

    MHB What are some important properties of the Commutator Group of D_n?

    Hey! :o We have that $D_n=\langle a,s\mid s^n=1=a^2, asa^{-1}=s^{-1}\rangle$. I want to show the following: $s^2\in D_n'$ $D_n'\cong \mathbb{Z}_n$ if $n$ is odd $D_n'\cong \mathbb{Z}_{\frac{n}{2}}$ if $n$ is even $D_n$ is nilpotent if and only if $n=2^k$ for some $k=1,2,\dots $ I...
  37. RJLiberator

    Does Group Cardinality Determine Element Order?

    Homework Statement If G is a group with n elements and g ∈ G, show that g^n = e, where e is the identity element. Homework EquationsThe Attempt at a Solution I feel like there is missing information, but that cannot be. This seems too simple: The order of G is the smallest possible integer n...
  38. RJLiberator

    Understanding the Center and Centralizer of a Dihedral Group

    Homework Statement If n ≥ 3, show that Z(D_n) = C(x) ∩ C(y). Homework Equations G is a group, g∈G C(g) = {h∈G: hg = gh } The Centralizer of g Z(G) = {h∈G: hg = gh for all g∈G} The center of G ∩ means the set of all points that fall in C(x) and C(y). Every element of D_n can be uniquely...
  39. M

    MHB Show that the group is not simple

    Hey! :o I want to show that: If $G$ contains a subgroup with index at most $4$ and $G$ has not a prime order, then $G$ is not a simple group. In my notes I found the following proposition: $$H\leq G, \ [G:H]=m \text{ and } |G|\not\mid m! \text{ then } G \text{ is not simple. }$$ We have...
  40. M

    I Sylow subgroup of some factor group

    Hi. I have the following question: Let G be a finite group. Let K be a subgroup of G and let N be a normal subgroup of G. Let P be a Sylow p-subgroup of K. Is PN/N is a Sylow p-subgroup of KN/N? Here is what I think. Since PN/N \cong P/(P \cap N), then PN/N is a p-subgroup of KN/N. Now...
  41. A. Neumaier

    A Loop quantum gravity and diffeomorphism group

    How is loop quantum gravity related to the principle of relativity, in particular to the diffeomorphism invariance of general relativity?
  42. M

    MHB Multiplicative group of matrices is nilpotent

    Hey! :o Let $M$ be a field and $G$ the multiplicative group of matrices of the form $\begin{pmatrix} 1 & x & y \\ 0 & 1 & z \\ 0 & 0 & 1 \end{pmatrix}$ with $x,y,z\in M$. I want to show that $G$ is nilpotent. Could you maybe give me some hints what we could do in this case? (Wondering)...
  43. A

    I What are the irreducible representations of point groups and how do I find them?

    As part of physical chemistry I am reading up group theory for molecular symmetries. I realize the way chemistry textbooks treat this must be very different from what mathematicians do. So I want to know how I take a point group, find the matrix operations and get the character table.For an C2...
  44. M

    MHB The group is isomorphic to one of the groups

    Hey! :o I want to show that if $G$ is of order $2p$ with $p$ a prime, then $G\cong \mathbb{Z}_{2p}$ or $G\cong D_p$. I have done the following: We have that $|G|=2p$, so there are $2$-Sylow and $p$-Sylow in $G$. $$P\in \text{Syl}_p(G) , \ |P|=p \\ Q\in \text{Syl}_2(G) , \ |Q|=2$$ Let $x\in...
  45. M

    MHB Show that each such group is solvable

    Hey! :o I am looking at the following exercise: Each group of order $p^2q$, with $p,q$ different primes, is solvable. To show this can we just say that it holds according to Burnside's Theorem ? (Wondering)
  46. S

    Does This Mapping Define a Group Homomorphism from ℤ_n to D_n?

    Homework Statement ℤ_n → D_n sending z modn → g^z where g is rotation by an nth of a turn. Homework Equations Group homomorphism imply θ(g_1*g_2)=θ(g_1)*θ(g_2) The Attempt at a Solution Before anything, I'd like to know if Group homomorphism imply θ(g_1+g_2)=θ(g_1)xθ(g_2) I've seen...
  47. G

    MHB How to Determine the Order of \( g^8 \) in a Group?

    Say an element $g$ in a group has order $28$. How do I find the order of say $g^8$?
  48. RJLiberator

    Order of (f°h) Group Homework Solution

    Homework Statement Let f,h ∈S_4 be described by: f(1) = 1 f(2) = 4 f(3) = 3 f(4) = 2 h(1) = 4 h(2) = 3 h(3) = 2 h(4) = 1 Express (f°h) in terms of its behavior on {1,2,3,4} and then find the order of (f°h). Homework EquationsThe Attempt at a Solution So, first I express (f°h) in terms of...
  49. Conservation

    Interesting compounds with alcohol functional group

    I'm looking for examples of some interesting compounds that contain alcohol functional group (please, no joke suggestions about various liquor). Bonus points for creativity/thinking-outside-the-box. Thanks.
  50. Einj

    A Euclidean signature and compact gauge group

    Hello everyone, I have been reading around that when performing the analytic continuation to Euclidean space (t\to-i\tau) one also has to continue the gauge field (A_t\to iA_4) in order to keep the gauge group compact. I already knew that the gauge field had to be continued as well but I didn't...
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