What is Abstract algebra: Definition and 457 Discussions

In algebra, which is a broad division of mathematics, abstract algebra (occasionally called modern algebra) is the study of algebraic structures. Algebraic structures include groups, rings, fields, modules, vector spaces, lattices, and algebras. The term abstract algebra was coined in the early 20th century to distinguish this area of study from the other parts of algebra.
Algebraic structures, with their associated homomorphisms, form mathematical categories. Category theory is a formalism that allows a unified way for expressing properties and constructions that are similar for various structures.
Universal algebra is a related subject that studies types of algebraic structures as single objects. For example, the structure of groups is a single object in universal algebra, which is called variety of groups.

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  1. micromass

    Insights Comments - How to self-study algebra. Part II: Abstract Algebra - Comments

    micromass submitted a new PF Insights post How to self-study algebra. Part II: Abstract Algebra https://www.physicsforums.com/insights/wp-content/uploads/2016/06/aastock6.png Continue reading the Original PF Insights Post.
  2. 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.
  3. micromass

    Schools In High School and Want to Do Advanced Mathematics? - Comments

    micromass submitted a new PF Insights post In High School and Want to Do Advanced Mathematics? https://www.physicsforums.com/insights/wp-content/uploads/2016/03/high school-math.png Continue reading the Original PF Insights Post.
  4. TyroneTheDino

    Proving or Disproving f(x) = √x as One-to-One and Onto: Homework Statement

    Homework Statement I am supposed to prove or disporve that ##f:\mathbb{R} \rightarrow \mathbb{R}## ##f(x)=\sqrt{x}## is onto. And prove or disprove that it is one to one Homework EquationsThe Attempt at a Solution I know for certain that this function is not onto given the codomain of real...
  5. 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...
  6. G

    Prove Isomorphic Groups: (\mathbb Z_4,_{+4}) and (\langle i\rangle, \cdot)

    Homework Statement Show that the group (\mathbb Z_4,_{+4}) is isomorphic to (\langle i\rangle,\cdot)? Homework Equations -Group isomorphism The Attempt at a Solution Let \mathbb Z_4=\{0,1,2,3\}. (\mathbb Z_4,_{+4}) can be represented using Cayley's table: \begin{array}{c|lcr} {_{+4}} & 0 &...
  7. RJLiberator

    Abstract Algebra: Bijection, Isomorphism, Symmetric Sets

    Homework Statement Suppose X is a set with n elements. Prove that Bij(X) ≅ S_n. Homework Equations S_n = Symmetric set ≅ = isomorphism Definition: Let G and G2 be groups. G and G2 are called Isomorphic if there exists a bijection ϑ:G->G2 such that for all x,y∈G, ϑ(xy) = ϑ(x)ϑ(y) where the...
  8. TyroneTheDino

    Arbitrary Union of Sets Question

    Homework Statement For each ##n \in \mathbb{N}##, let ##A_{n}=\left\{n\right\}##. What are ##\bigcup_{n\in\mathbb{N}}A_{n}## and ##\bigcap_{n\in\mathbb{N}}A_{n}##. Homework Equations The Attempt at a Solution I know that this involves natural numbers some how, I am just confused on a...
  9. RJLiberator

    [Abstract Algebra] GCD and Relatively Prime Proof

    Homework Statement If gcd(f(x),g(x)) = 1 and m,n ∈ ℕ, show that gcd(f(x)^m, g(x)^n) = 1. Homework EquationsThe Attempt at a Solution So I had previously proved this for non-polynomials: gcd(a,b)=1 then gcd(a^n,b^n)=1 Proof: a = p1*p2*...*pn b = p1*p2*...*pm then a^n = p1^n*p2^n*...*pn^n...
  10. RJLiberator

    [Abstract Algebra] Field and Polynomial Root problem

    Homework Statement Suppose a field F has n elements and F=(a_1,a_2,...,a_n). Show that the polynomial w(x)=(x-a_1)(x-a_2)...(x-a_n)+1_F has no roots in F, where 1_f denotes the multiplicative identity in F. Homework EquationsThe Attempt at a Solution Strategy: We have this polynomial...
  11. RJLiberator

    Factoring Polynomials [Abstract Algebra]

    Homework Statement 1. Let g(x) = x^4+46. a) Factor g(x) completely in ℚ[x]. b) Factor g(x) completely in ℝ[x]. c) Factor g(x) completely in ℂ[x]. 2. Completely factor the given polynomial in ℤ_5. [4]_5 x^3 + [2]_5 x^2 + x + [3]_5 Homework Equations ℚ = {m/n / m and n belong to Z, m is not...
  12. HaLAA

    Find all irreducible polynomials over F of degree at most 2

    Homework Statement Let F = {0,1,α,α+1}. Find all irreducible polynomials over F of degree at most 2. Homework EquationsThe Attempt at a Solution To determine an irreducible polynomial over F, I think it is sufficient to check the polynomial whether has a root(s) in F, So far, I got...
  13. RJLiberator

    Abstract algebra Polynomials and Prime

    Homework Statement Let g(x) ∈ ℤ[x] have degree at least 2, and let p be a prime number such that: (i) the leading coefficient of g(x) is not divisible by p. (ii) every other coefficient of g(x) is divisible by p. (iii) the constant term of g(x) is not divisible by p^2. a) Show that if a ∈ ℤ...
  14. RJLiberator

    Finding coefficients for reducibility (Abstract Algebra)

    Homework Statement Find all real numbers k such that x^2+kx+k is reducible in ℝ[x]. Homework EquationsThe Attempt at a Solution This seems like it is simple, but it is new to me so I am looking for confirmation. We know we can find the roots of a polynomial with b^2-4ab. We want b^2-4ab to be...
  15. RJLiberator

    Simple Abstract Algebra Proof: T(0_r) = 0_s

    Homework Statement Let T:R-> S be a homomorphism of rings. Show that T(0_r) = 0_s. Homework EquationsThe Attempt at a Solution First off, the terminology used is kinda confusing. I take 0_r to be the zero in R. Is this correct? For some reason I recall my teacher quickly saying that it was...
  16. M

    Polynomial splits over simple extension implies splitting field?

    This is a question that came about while I attempting to prove that a simple extension was a splitting field via mutual containment. This isn't actually the problem, however, it seems like the argument I'm using shouldn't be exclusive to my problem. Here is my attempt at convincing myself that...
  17. RJLiberator

    Abstract Algebra: Another Ring Proof

    Homework Statement Let R be a ring and suppose r ∈R such that r^2 = 0. Show that (1+r) has a multiplicative inverse in R. Homework Equations A multiplicative inverse if (1+r)*x = 1 where x is some element in R. The Attempt at a Solution We know we have to use two facts. 1. Multiplicative...
  18. RJLiberator

    Abstract Algebra: Ring Proof (Multiplicative Inverse)

    Homework Statement Suppose R is a commutative ring with only a finite number of elements and no zero divisors. Show that R is a field. Homework Equations Unit is an element in R which has a multiplicative inverse. If s∈R with r*s = 1. A zero divisor is an element r∈R such that there exists...
  19. P

    Solutions to Hungerford's "Abstract Algebra" 3rd Ed.

    I'm taking an abstract algebra course that uses Hungerford's "An Introduction to Abstract Algebra" 3rd Ed. And while I feel like I'm following the material sufficiently and can do most of the proofs it's hard to learn and practice the material without a solutions guide. How am I supposed to know...
  20. DeldotB

    A few questions about a ring of polynomials over a field K

    Homework Statement Consider the ring of polynomails in two variables over a field K: R=K[x,y] a)Show the elements x and y are relatively prime b) Show that it is not possible to write 1=p(x,y)x+q(x,y)y with p,q \in R c) Show R is not a principle ideal domain Homework Equations None The...
  21. G

    Cyclic Quotient Group: Is My Reasoning Sound?

    Hi everyone. So it's apparent that G/N cyclic --> G cyclic. But the converse does not seem to hold; in fact, from what I can discern, given N cyclic, all we need for G/N cyclic is that G is finitely generated. That is, if G=<g1,...,gn>, we can construct: G/N=<(g1 * ... *gn)*k> Where k is the...
  22. DeldotB

    Compute the G.C.D of two Gaussian Integers

    Homework Statement Hello all I apologize for the triviality of this: Im new to this stuff (its easy but unfamiliar) I was wondering if someone could verify this: Find the G.C.D of a= 14+2i and b=21+26i . a,b \in \mathbb{Z} [ i ] - Gaussian Integers Homework Equations None The Attempt...
  23. DeldotB

    Show a group is a semi direct product

    Homework Statement Good day, I need to show that S_n=\mathbb{Z}_2(semi direct product)Alt(n) Where S_n is the symmetric group and Alt(n) is the alternating group (group of even permutations) note: I do not know the latex code for semi direct product Homework Equations none The Attempt at...
  24. DeldotB

    Why a group is not a direct or semi direct product

    Homework Statement Good day all! (p.s I don't know why every time I type latex [ tex ] ... [ / tex ] a new line is started..sorry for this being so "spread" out) So I was wondering if my understanding of this is correct: The Question asks: "\mathbb{Z}_4 has a subgroup is isomorphic to...
  25. DeldotB

    Showing two groups are *Not* isomorphic

    Homework Statement Good day, I need to show: \mathbb{Z}_{4}\oplus \mathbb{Z}_{4} is not isomorphic to \mathbb{Z}_{4}\oplus \mathbb{Z}_{2}\oplus \mathbb{Z}_{2} Homework Equations None The Attempt at a Solution I was given the hint that to look at the elements of order 4 in a group. I know...
  26. DeldotB

    Using the Second Isomorphism (Diamond Isomorphism) Theorem

    Homework Statement Good day all, Im completely stumped on how to show this: |AN|=(|A||N|/A intersect N|) Here: A and N are subgroups in G and N is a normal subgroup. I denote the order on N by |N| Homework Equations [/B] Second Isomorphism TheoremThe Attempt at a Solution Well, I know...
  27. N

    Abstract Algebra: Automorphisms

    I have a question about Automorphisms. Please check the following statement for validity... An automorphism of a group should map generators to generators. Suppose it didn't, well then the group structure wouldn't be preserved and since automorphisms are homomorphisms this would be a...
  28. N

    Understanding the Coproduct in Grp as a Universal Object

    Homework Statement Coproducts exist in Grp. This starts on page 71. of his Algebra. Homework Equations [/B] Allow me to present the proof in it's entirety, modified only where it's convenient or necessary for TeXing it. I've underlined areas where I have issues and bold bracketed off my...
  29. B

    Algebra Comments about "Topics in Algebra" by I.N. Hertsein?

    Dear Physics Forum advisers, Today, I got two gifts from my research mentor: "Topics in Algebra" by I.N. Herstein and "Abstract Algebra" by Dummit/Foote. I am very happy and grateful for his gifts, but I already have been studying the abstract algebra through Michael Artin and Hoffman/Kunze...
  30. N

    [itex]\hom_A(-,N)[/itex]Functor Takes Coproducts to Products

    A couple of notes first: 1. \hom_{A}(-,N) is the left-exact functor I'm referring to; Lang gives an exercise in the section preceeding to show this. 2. This might be my own idiosyncrasy but I write TFDC to mean 'The following diagram commutes' 3. Titles are short, so I know that the hom-functor...
  31. B

    Seeking Your Advice on My Course Planning

    Dear Physics Forum advisers, I am a rising college junior in U.S. with a major in mathematics, and an aspiring applied mathematician. I apologize for this sudden interruption, but I wrote this email to seek your advice on my current problem on the course selection. I will very soon be...
  32. N

    Abstract Algebra: Dummit and Foote Exercise

    This isn't homework, I'm just trying to refresh my memory on cyclic groups. My question is, in this problem solution, how does ##{\sigma_i}^m=1## follow from ##\sigma_i## being disjoint?
  33. N

    Abstract Algebra Homework Solution - Check Ring Homomorphism

    Homework Statement Hello guys So I have the following problem, given the mapping above I have to check weather it's ring homomorphism, and maybe monomorphism or epimorphism. The Attempt at a Solution So the mapping is obviously well defined, and I have proven it's homomorphism, and it's...
  34. B

    Algebra Seeking Recommendation on Abstract Algebra textbooks

    Dear Physics Forum advisers, My name is Phoenix, a sophomore with major in mathematics and an aspiring applied mathematician in the theoretical computing. I wrote this email to seek your recommendation on the textbooks for abstract algebra. I want to self-study the abstract algebra during...
  35. HaLAA

    Show that Q_F is not a division ring.

    Homework Statement Let F be a finite field of characteristic p∈{2,3,5}. Consider the quaternionic ring, Q_F={a_1+a_i i+a_j j+a_k k|a_1,a_i,a_j,a_k ∈ F}. Prove that Q_F is not a division ring. Homework EquationsThe Attempt at a Solution Let α=1+i,β=1+i+j∈QF. Then...
  36. HaLAA

    Show √ 2 + √ 3 algebraic over Q

    Homework Statement Show √ 2 + √ 3 algebraic over Q. Find its degree over Q. Prove the answer. Homework EquationsThe Attempt at a Solution Let ##\alpha= \sqrt{2}+\sqrt{3}\in \mathbb{R}##, then ##\alpha^4-10\alpha^2+1=0## which is a root of ##f(x)=x^4-10x^2+1## where ##f(x)## in...
  37. HaLAA

    FInd non-zero elements are primitive in a field

    Homework Statement Construct $\mathbb{F}_{16}$ as a quotient of $\mathbb{Z}_2[X]$. How many non-zero elements are primitive in this field? Calculate $|GL2_(\mathbb{F}_16)|$. Homework Equations Primitive Theorem The Attempt at a Solution For the first question, I don't know how to construct...
  38. B

    Taking Real Analysis, Abstract Algebra, and Linear Algebra

    Dear Physics Forum advisers, I am a college sophomore in US with a major in mathematics, and an aspiring algebraic number theorist and cryptographer. I wrote this email to seek your advice about taking the Analysis I (Real Analysis I), Abstract Algebra I, and Linear Algebra with Proofs. At...
  39. HaLAA

    Is F Isomorphic to Its Own Quotient by {0}?

    Homework Statement Let F be a field. Show that F is isomorphic to F/{0} Homework EquationsThe Attempt at a Solution By the first ring isomorphic theorem, kernel of the homomorphism is an ideal which is either {0} or I. Hence F isomorphic to F/{0} I think I misunderstood the problem can...
  40. HaLAA

    Show the group of units in Z_10 is a cyclic group of order 4

    Homework Statement Show that the group of units in Z_10 is a cyclic group of order 4 Homework EquationsThe Attempt at a Solution group of units in Z_10 = {1,3,7,9} 1 generates Z_4 3^0=1, 3^1=3, 3^2=9, 3^3= 7, 3^4= 1, this shows <3> isomorphic with Z_4 7^0=1 7^1= 7, 7^2= 9 7^3=3 7^4=1, this...
  41. heff001

    Abstract Algebra self study question -- Are Calc I, II, III prerequisites?

    Hi, Are Calculus I, II, III courses a prerequisite requirement for studying Abstract Algebra? I have read that Proofs and a willingness to work hard is. I am studying Logic and Set Theory and want to study Abstract Algebra in the distant future. I am focused on Foundational and Pure...
  42. HaLAA

    Show the range of f is isomorphic to a quotient of z

    Homework Statement Let G be any group and a in G, define f: Z → G by f(n) = a^n Apply any isomorphism theorem to show that range of f is isomorphic to a quotient group of Z Homework EquationsThe Attempt at a Solution The range of f is a^n , then quotient group of Z is Z/nZ Apply the first...
  43. heff001

    Pure Mathematics study - question

    I am planning to study the following pure mathematics areas (on my own) and wanted to know if this is the best sequence: 1- Formal Logic 2 -Philosophical Logic 3- Sentential Logic 4- Predicate Logic 5- Symbolic Logic 6 -Set Theory 7 -Pure Mathematics (Intro, Pure Math I and II and Hardy) -...
  44. H

    Algebra Abstract Algebra Book: Find the Best Textbook for Rigorous Understanding

    Hello, A couple of years ago I studied abstract algebra from Dummit and Foote. However, I was never able to gain the intuition on the subject that I would like from that book. I want to study the subject again, and I want to use a different book this time around - one that covers a lot of...
  45. Avatrin

    Book for abstract algebra (group and galois theory)

    Hi I recently read a book called "The fundamental theorem of algebra" by Fine and Rosenberger. It focused specifically on polynomials, and proved the theorem using several fields of mathematics; Two of the proofs were algebraic. Abstract algebra has been very difficult for me; Mostly because...
  46. HaLAA

    Show (H,+) is isomorphic to (C,+)

    Homework Statement Let, M={ (a -b) (b a):a,b∈ℝ}, show (H,+) is isomorphic as a binary structure to (C,+) Homework Equations Isomorphism, Group Theory, Binary Operation The Attempt at a Solution Let a,b,c,d∈ℝ Define f : M→ℂ by f( (a -b) (b a) ) = a+bi 1-1: Suppose f( (a -b) (b a) )= f( (c...
  47. R

    Programs Possible double major: abstract algebra or otherwise?

    I found out I can pick up a second major in math should I elect to take a two semester sequence in abstract algebra. My first major is in chemical engineering. Right now, I plan on taking a two semester sequence in either: 1) probability with measure theory, 2) abstract algebra (Dummit and...
  48. T

    Abstract Algebra; Group Theory Question

    Let N be a normal subgroup of a group G and let f:G→H be a homomorphism of groups such that the restriction of f to N is an isomorphism N≅H. Prove that G≅N×K, where K is the kernel of f. I'm having trouble defining a function to prove this. Could anyone give me a start on this?
  49. F

    Cycle Decomposition of Permutations

    Homework Statement Let α = (α1α2...αs) be a cycle, for positive integers α1α2...αs. Let π be any permutation that παπ-1 is the cycle (π(α1)πα2...π(αs)). Homework EquationsThe Attempt at a Solution I started by choosing a specific α and π, and tried finding παπ-1 to give myself some idea of...
  50. R

    Finding a normal subgroup H of Zmn of order m

    Homework Statement Find a normal subgroup H of Zmn of order m where m and n are positive integers. Show that H is isomorphic to Zm. Homework EquationsThe Attempt at a Solution I am honestly not even sure where to start. My initial thoughts were if Zmn was isomorphic to Zm x Zn then I could...
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