Mathematical Excursions: Side Trips along Paths Not Generally Traveled in Elementary Courses in Mathematics is a book on popular mathematics. It was written by Helen Abbot Merrill, published in 1933 by the Norwood Press,[1][2][3][4][5] and reprinted (posthumously) by Dover Publications in 1957.[6][7]
The book is written for a general audience,[1] and is intended to spark the interest of high school students in mathematics.[4]In general, only high school levels of algebra and geometry are needed to appreciate the book and solve its problems.[1]It could be used as individual reading, or in mathematics clubs,[2]and also for mathematics teachers looking for examples and demonstrations for their classes.[5]
I have a disk of radius R removed from the plane. Brownian excursions are emanated from infinity. I am tasked to find a probability that the brownian motion impacts an arc of the disk boundary. I am also asked to do this for a point outside the disk and for replacing the disk with an ellipse; which part of the ellipse receives more particles?
Let $\mathrmB_e(t)$ be a Brownian excursion on $[0,1]$. I would like to find$$ \mathbbE\left[ \int_0^1 \mathrmB_e(t) dt \right]$$In this post it is explained that the integral of a Brownian motion is Gaussian. Following the answers it states that if $\mathrmB(t)$ is a Brownian motion, then$$ \int_0^\tau \mathrmB(t) dt \sim N\left(0, \int_0^\tau(\tau-s)^2 d s\right) $$That would be $\sim N\left(0, \frac13\right)$ on $[0,1]$.
It's easy to prove that $x \sin \frac 1 x$ is uniformly continuous, but hard to find a specific $\delta$ for a given $\varepsilon$. That leads to excursions like: How can we find a $\delta$? (A. Use the Prosthaphaeresis identities). Is there an optimal $\delta$? (A. Yes, and it's well defined, although surprisingly discontinuous and difficult to compute.)
A proof that if $f(x+y) = f(x) + f(y)$ and $f$ is continuous at $0$, then $f$ is continuous everywhere leads to the excursion: Are there additive nowhere continuous functions? (A. Yes! They're surprisingly wild, being dense in the plane, yet extremely regular, being invariant under a family of translations.) Exploring this lead to a better understanding of infinite dimension vector spaces.
Clearly, these excursions have what to offer, but also have costs. On the one hand, it's great to stimulate independent exploration. On the other, mathematics is learned by doing, not searching and scanning: With limited time available, is it worth taking away from the matter at hand, which is designed at the right difficulty for me to actually do, to explore tangents which I can only read about? And is it worth taking away from curated material selected for its importance and replace it with excursions that may, even if fruitful, be random?
I'd argue that exercises from a good text can do exactly that: carefully control the challenge questions to give a predictable research experience. Is that an argument to avoid excursions entirely, and simply find a text with good exercises?
What shapes do you get when you spin a cube on one of its vertices? This article explores the algebraic aspects of a spinning cube and establishes equations for the two cones and the hyperboloid using secondary school mathematics. Both the analysis and the verification take advantage of dynamic mathematics learning technologies.
The course is intended to provide exposure to a variety ofmathematical ideas. The emphasis is on topics which are interestingand where the conclusion of a mathematical development can beunderstood with only high school algebra as background. These topicscan involve parts of mathematics which are significant in publicaffairs; such as voting paradoxes, polling data, and schedulingmethods. Other topics involve numbers or shapes to reveal beauty andelegance in mathematics.
MAT 107 - Excursions in Mathematics (3)Basic principles and techniques of mathematics. May include theory of sets, logic, number theory, geometry, probability and statistics, consumer mathematics. Emphasis on unity of thought and consistency of approach to problem solving. History and relevance of mathematics for growth of civilizations. Prerequisite(s); if any: MAT 100 , or satisfactory performance in Mathematics Placement Test administered by mathematics department, or permission of instructor.
Too often math gets a bad rap, characterized as dry and difficult. But, Alex Bellos says, "math can be inspiring and brilliantly creative. Mathematical thought is one of the great achievements of the human race, and arguably the foundation of all human progress. The world of mathematics is a remarkable place."
If an integrable classical Hamiltonian H describing bound motion depends on parameters which are changed very slowly then the adiabatic theorem states that the action variables I of the motion are conserved. Here the fate of the angle variables is analysed. Because of the unavoidable arbitrariness in their definition, angle variables belonging to distinct initial and final Hamiltonians cannot generally be compared. However, they can be compared if the Hamiltonian is taken on a closed excursion in parameter space so that initial and final Hamiltonians are the same. The result shows that the angle variable change arising from such an excursion is not merely the time integral of the instantaneous frequency omega =dH/dI, but differs from it by a definite extra angle which depends only on the circuit in parameter space, not on the duration of the process. The 2-form which describes this angle variable holonomy is calculated.
We develop a technique for "partially collapsing" one Markov process to produce another. The state space of the new Markov process is obtained by a pinching operation that identifies points of the original state space via an equivalence relationship. To ensure that the new process is Markovian we need to introduce a randomized twist according to an appropriate probability kernel. Informally, this twist randomizes over the uncollapsed region of the state space when the process leaves the collapsed region. The "Markovianity" of the new process is ensured by suitable intertwining relationships between the semigroup of the original process and the pinching and twisting operations. We construct the new Markov process, identify its resolvent and transition function and, under some natural assumptions, exhibit a core for its generator. We also investigate its excursion decomposition. We apply our theory to a number of examples, including Walsh's spider and a process similar to one introduced by Sowers in studying stochastic averaging.
N2 - We develop a technique for "partially collapsing" one Markov process to produce another. The state space of the new Markov process is obtained by a pinching operation that identifies points of the original state space via an equivalence relationship. To ensure that the new process is Markovian we need to introduce a randomized twist according to an appropriate probability kernel. Informally, this twist randomizes over the uncollapsed region of the state space when the process leaves the collapsed region. The "Markovianity" of the new process is ensured by suitable intertwining relationships between the semigroup of the original process and the pinching and twisting operations. We construct the new Markov process, identify its resolvent and transition function and, under some natural assumptions, exhibit a core for its generator. We also investigate its excursion decomposition. We apply our theory to a number of examples, including Walsh's spider and a process similar to one introduced by Sowers in studying stochastic averaging.
AB - We develop a technique for "partially collapsing" one Markov process to produce another. The state space of the new Markov process is obtained by a pinching operation that identifies points of the original state space via an equivalence relationship. To ensure that the new process is Markovian we need to introduce a randomized twist according to an appropriate probability kernel. Informally, this twist randomizes over the uncollapsed region of the state space when the process leaves the collapsed region. The "Markovianity" of the new process is ensured by suitable intertwining relationships between the semigroup of the original process and the pinching and twisting operations. We construct the new Markov process, identify its resolvent and transition function and, under some natural assumptions, exhibit a core for its generator. We also investigate its excursion decomposition. We apply our theory to a number of examples, including Walsh's spider and a process similar to one introduced by Sowers in studying stochastic averaging.
Most of the mathematical books which are not textbooks are written for rather learned people, but this book is not written for the learned. All the mathematical knowledge that it calls for is Algebra and Geometry, enough to show you that those subjects can be very entertaining. One pleasant feature of mathematics is that we do not have to know a great deal about it in order to get amusement from it, and a still more pleasant one is that the farther we go the more we find to surprise and entertain us.
On the one side is mathematics, and its capacity to enhance the understanding of architecture, both aesthetic aspects such as symmetry and proportion, and structural aspects such as loads, thrusts, and reactions. On the other side is architecture, as an attractive setting that allows basic abstract and abstruse mathematics to become visible and more transparent.
The remaining challenge was to cover and seal the outer surfaces of the shells. This required a sophisticated tile system. Tiles configured in V-shaped formations, or lids, were locked into place with brackets and bolts that could be adjusted to give them the precise orientation they needed to have on the spherical surface. This required more mathematics and computer analysis. When the last lid was lowered into position in January 1967, the roof vaults of the opera complex were finally complete.
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