A mathematical proof is an inferential argument for a mathematical statement, showing that the stated assumptions logically guarantee the conclusion. The argument may use other previously established statements, such as theorems; but every proof can, in principle, be constructed using only certain basic or original assumptions known as axioms, along with the accepted rules of inference. Proofs are examples of exhaustive deductive reasoning which establish logical certainty, to be distinguished from empirical arguments or non-exhaustive inductive reasoning which establish "reasonable expectation". Presenting many cases in which the statement holds is not enough for a proof, which must demonstrate that the statement is true in all possible cases. An unproven proposition that is believed to be true is known as a conjecture, or a hypothesis if frequently used as an assumption for further mathematical work.Proofs employ logic expressed in mathematical symbols, along with natural language which usually admits some ambiguity. In most mathematical literature, proofs are written in terms of rigorous informal logic. Purely formal proofs, written fully in symbolic language without the involvement of natural language, are considered in proof theory. The distinction between formal and informal proofs has led to much examination of current and historical mathematical practice, quasi-empiricism in mathematics, and so-called folk mathematics, oral traditions in the mainstream mathematical community or in other cultures. The philosophy of mathematics is concerned with the role of language and logic in proofs, and mathematics as a language.
Okay, these are my last questions and then I'll get out of your hair for a while.
For 1, I have already done a proof by contradiction, but I'm supposed to also do a direct proof. Seems like it should be simple?
For 2, this seems obvious because it's the definition of an integral. My delta is...
I have no idea how to incorporate the limit into the basic definitions for a Riemann integral? All we have learned so far is how to define a Riemann integral and the properties of Riemann integrals. What should I be using for this?
Note: Please only give hints please! No answers because I want the satisfaction of solving it.
1. Homework Statement
A mass M at height h above flat round and falling vertically with velocity v breaks up explosively into 2 parts. The kinetic energy given to the system in the explosion is E...
Homework Statement
Suppose R1 and R2 are relations on A and R1 ⊆ R2.
Let S1 and S2 be the transitive closures of R1 and R2 respectively.
Prove that S1 ⊆ S2.
Please check my proof and please explain my mistakes. thank you for taking the time to help.
Homework Equations
N/A
The Attempt at a...
{\displaystyle \sum_{n=1}^{\infty}a_{n}}
is converage, For N\in
\mathbb{N}\sum_{n=N+1}^{\infty}an
is also converage
proof that \lim_{N\rightarrow\infty}(\sum_{n=N+1}^{\infty}an)=0
{\displaystyle \sum_{n=1}^{\infty}a_{n}}
is converage, For N\in
\mathbb{N}
\sum_{n=N+1}^{\infty}an
is...
Homework Statement
I am trying to understand the proof that ##\lim S## is a closed set in the metric space ##M##, where ##\lim S = \{ p \in M ~|~ p \mbox{ is a limit point of } S\}##.
Here is the definition of a limit point: ##p## is a limit point of ##S## if and only if there exists a...
Let $\beta$ be an ordinal.
Prove that $A\cap \bigcup\beta=\bigcup\{A\cap X\mid X \in \beta\}$
I'm not sure on this. It looks a bit like union distributing over intersection. Please help.
Homework Statement
I need to prove by induction that ##(n!)^{2} \le (2n)!##. I'm pretty sure about my preliminary work, but I just need some suggestions for the end.
Homework Equations
It is well known from a theorem that if ##a \le b## and ##c \ge 0##, then ##ca \le cb##.
The Attempt at a...
I am very open minded and I would fully trust in Cantor's diagonal proof yet this question is the one that keeps holding me back. My question is the following:
In any given infinite set, there exist a certain cardinality within that set, this cardinality can be holded as a list. When you change...
This is a simple exercise from Spivak and I would like to make sure that my proof is sufficient as the proof given by Spivak is much longer and more elaborate.
Homework Statement
Prove that \lim_{x\to a} f(x) = \lim_{h\to 0} f(a + h)
Homework EquationsThe Attempt at a Solution
By the...
Quantum theory, although hard to understand with intuition has a lot of experimental proof. Do the more modern theories e.g. String theory, or black hole theories have any experimental proof, or are they theories that the mathematics have led to?
Without proof, do they deserve so much credit...
Hi.
I have been looking at the proof that the parity operator is hermitian in 3-D in the QM book by Zettili and I am confused by the following step
∫ d3r φ*(r) ψ(-r) = ∫ d3r φ*(-r) ψ(r)
I realize that the variable has been changed from r to -r. In 3-D x,y,z this is achieved by taking the...
Homework Statement
Let A,B,C,D be commuting n-square matrices. Consider the 2n-square block matrix ##M= \begin{bmatrix}
A & B \\
C & D \\
\end{bmatrix}##. Prove that ##\left | M \right |=\left | A \right |\left | D \right |-\left | B \right |\left | C \right |##. Show that the result may not be...
The sum of the $k$ th power of n variables $\sum_{i=1}^{i=n} x_i^k$ is a symmetric polynomial, so it can be written as a sum of the elementary symmetric polynomials.
I do know about the Newton's identities, but just with the algorithm of proving the symmetric function theorem, what should we do...
Homework Statement
Hi
I am looking at the proof attached for the theorem attached that:
If ##s \in R##, then ##\sum'_{w\in\Omega} |w|^-s ## converges iff ##s > 2##
where ##\Omega \in C## is a lattice with basis ##{w_1,w_2}##.
For any integer ##r \geq 0 ## :
##\Omega_r := {mw_1+nw_2|m,n \in...
So the definition of a bounded sequence is this:
A sequence ##(x_{n})## of real numbers is bounded if there exists a real number ##M>0## such that ##|x_{n}|\le M## for each ##n##
My question is pretty simple. How does one choose the M, based on the sequence in order to arrive at the...
I agree that this could have been done more simply(i'm not looking for an alternative proof), but I don't understand how it is wrong, any insight?
Since Dn is an dihedral group, we know its elements are symmetries, Dn = (R1,R2,R3...Ri) and since R is a symmetry, we know it's a permutation, so...
I'm in the 6th week of a well-known MOOC course created by Kevin Devlin, "Introduction to Mathematical Thinking." I enjoy the course & did well in the first weeks with conditionals and truth tables, etc.; however now that we are entering into proofs, I'm running into trouble with algebra...
Repeatedly apply $\binom{n}{r}= \binom{n-1}{r}+\binom{n-1}{r-1}$ to show:
$$\binom{n}{r}=\sum_{i=1}^{r+1}\binom{n-i}{r-i+1}$$
The closest i got was showing you could show different iterations with the binomial coefficients (Pascal's Triangle).
Homework Statement
Hi
I have questions on the attached lemma and proof.
##f(z)## is an elliptic function here, and non-consant ##\Omega## is a period lattice.
So the idea behind the proof is this is a contradiction because the function was assumed to be non-constant but by the theorem that...
From Courant's Differential and Integral Calculus p.13,
In an ordinary system of rectangular co-ordinates, the points for which both co-ordinates are integers are called lattice points. Prove that a triangle whose vertices are lattice points cannot be equilateral.
Proof: Let ##A=(0,0)...
Homework Statement
they say 1. ##e^{ln x}= x ## and 2.##e^-{ln(x+1)}= \frac 1 {x+1}## how can we prove this ##e^{ln x}= x ## and also ##e^-{ln(x+1)}= \frac 1 {x+1}##?
Homework EquationsThe Attempt at a Solution
let ## ln x = a## then
##e^a= x,
## a ln e= x,##
→a= x, where
## ln x= x
I am reading Paul E. Bland's book, "Rings and Their Modules".
I am focused on Section 6.1 The Jacobson Radical ... ...
I need help with the proof of Proposition 6.1.7 ... Proposition 6.1.7 and its proof read as follows:
In the above text from Bland, in the proof of (1), we read the...
I'm stuck on this proof question:
(¬(Q⇒¬P) ∧ ¬((Q∧¬R)⇒¬P )) ⇔ ¬(R ∨ (P ⇒¬Q))
I've tried to get rid of the negation and implications but I keep going in circles and I'm getting nowhere near to the equivalence required. I would appreciative if anyone can help me solve this because it's really...
Homework Statement
Prove the formula for inertia of a ring (2D circle) about its central axis.
Homework Equations
I = MR^2
Where:
M: total mass of the ring
R: radius of the ring
The Attempt at a Solution
- So I need to prove the formula above.
- First, I divide the ring into 4...
Homework Statement
Does anyone know of a simple proof for this: https://s30.postimg.org/tw9cjym9t/expect.png
E(X) = E(X|S)P(S) + E(X|S_c)P(S_c)
X is a random variable,
S is an a scenario that affects the likelihood of X. So P(S) is the probability of the scenario occurring and and P(S_c) is...
Whittaker (1st Edition, 1902) P.132, gives two proofs of Fourier's theorem, assuming Dirichlet's conditions. One proof is Dirichlet's proof, which involves directly summing the partial sums, is found in many books. The other proof is an absolutely stunning proof of Fourier's theorem in terms of...
Homework Statement
Prove that a set S of vectors is linearly independent if and only if each finite subset of S is linearly independent.
Homework EquationsThe Attempt at a Solution
I think that that it would be easier to prove the logically equivalent statement: Prove that a set S of vectors...
Homework Statement
[/B]
Theorem attached.
I know the theorem holds for a discrete subgroup of ##C## more generally, ##C## the complex plane, and that the set of periods of a non-constant meromorphic function are a discrete subset.
I have a question on part of the proof (showing the second...
Homework Statement
Find all integer solutions to x2 + y2 + z2 = 51. Use "without loss of generality."
Homework Equations
The Attempt at a Solution
My informal proof attempt:
Let x, y, z be some integers such that x, y, z = (0 or 1 or 2 or 3) mod 4
Then x2, y2, y2 = (0 or 1) mod 4
So x2 +...
Homework Statement
Let A and B be elements of the line EF such that A=/B prove that the line AB=EFHomework Equations
Axiom that two points determine a unique line and that the intersection of two lines has two distinct points then these lines are the same.
The Attempt at a Solution
[/B]
If A...
Hi,
My notes say that hurwitz identity currently has no elementary proof?
One way to prove the identity is through modular forms: to consider Eisenstein series, ##E_4^2## and ##E_8## , note that the dimension of space of modular functions of weight 8 is one, find the constant of...
Homework Statement
Hi,
As part of the proof that :
the set of periods ##\Omega_f ## of periods of a meromorphic ##f: U \to \hat{C} ##, ##U## an open set and ##\hat{C}=C \cup \infty ##, ##C## the complex plane, form a discrete set of ##C## when ##f## is a non-constant
a step taken in the...
Homework Statement Homework EquationsThe Attempt at a Solution
Hi
How do I go about showing ##0 \leq \frac{2x}{\pi} \leq sin x ##?
for ## 0 \leq x \leq \pi /2 ##
I am completely stuck where to start.
Many thanks.
(I see it is a step in the proof of Jordan's lemma, but I'm not interested in...
is this a practical way of proving math theorems? i asked because when i tried, it seemed difficult for me to decide as to how exactly i should translate theorems and given statements into logical forms and since there are so many different ways, i do not know which one is correct.
For example...
(From Hoffman and Kunze, Linear Algebra: Chapter 6.7, Exercise 11.) Note that ##V_j^0## means the annihilator of the space ##V_j##. V* means the dual space of V.
1. Homework Statement
Let V be a vector space, Let ##W_1 , \cdots , W_k## be subspaces of V, and let
$$V_j = W_1 + \cdots + W_{j-1}...
When I hear that mass of a particle has managed to hop through a solid barrier ..it tells me that the mass was a variable and not physical at the time.
Hello! (Wave)
We say that the space $\Omega$ satisfies the exterior sphere condition at the point $x_0 \in \partial{\Omega}$ if there is a $y \notin \overline{\Omega}$ and a number $R>0$ such that $\overline{\Omega} \cap \overline{B_y(R)}=\{ x_0 \}$.
Let the function $\phi \in...
Homework Statement
Show that if ##G = \langle x \rangle## is a cyclic group of order ##n \ge 1##, then a subgroup ##H## is maximal; if and only if ##H = \langle x^p \rangle## for some prime ##p## dividing ##n##
Homework Equations
A subgroup ##H## is called maximal if ##H \neq G## and the only...
Homework Statement
Let ##f:X \to Y##. Show that
##f## not uniform continuous on ##X## ##\Longleftrightarrow## ##\exists \epsilon > 0## and sequences ##(p_n), (q_n)## in ##X## so that ##d_X(p_n,q_n)\to 0 ## while ##d_Y(f(p_n),f(q_n))\ge \epsilon##.
Homework Equations
Let ##f:X\to Y##. We say...
Homework Statement
Let ##E## be a metric subspace to ##M##. Show that ##E## is closed in ##M## if ##E## is complete. Show the converse if ##M## is complete.
Homework Equations
A set ##E## is closed if every limit point is part of ##E##.
We denote the set of all limit points ##E'##.
A point...
Homework Statement
Let ##E \subseteq M##, where ##M## is a metric space.
Show that
##p\in \overline E = E\cup E' \Longleftrightarrow## there exists a sequence ##(p_n)## in ##E## that converges to ##p##.
##E'## is the set of limit points to ##E## and hence ##\overline E## is the closure of...
Homework Statement
Prove that if a² + ab + b² = 0 then a = 0 and b = 0
Hint: Recall the factorization of a³-b³. (Another solution will be discussed later when speaking about quadratic equations.)
Homework Equations
a² + ab + b² is close to a² + 2ab + b² = (a+b)²
a³-b³=(a-b)(a²+ab+b²)
The...
Hola, I tried to give a proof of this theorem and then check it against the one given by my book(Fasano, Marmi - Analytical Mechanics); I feel like mine seems reasonable and pretty intuitive, but the one on the book is a bit different and I don't really understand it completely, so I'd like to...