Logarithms and Exponentiation Guide
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The Enigmatic Number E: a History in Verse and Its Uses in the Mathematics Classroom
To appear in MAA Loci: Convergence The Enigmatic Number e: A History in Verse and Its Uses in the Mathematics Classroom Sarah Glaz Department of Mathematics University of Connecticut Storrs, CT 06269 [email protected] Introduction In this article we present a history of e in verse—an annotated poem: The Enigmatic Number e . The annotation consists of hyperlinks leading to biographies of the mathematicians appearing in the poem, and to explanations of the mathematical notions and ideas presented in the poem. The intention is to celebrate the history of this venerable number in verse, and to put the mathematical ideas connected with it in historical and artistic context. The poem may also be used by educators in any mathematics course in which the number e appears, and those are as varied as e's multifaceted history. The sections following the poem provide suggestions and resources for the use of the poem as a pedagogical tool in a variety of mathematics courses. They also place these suggestions in the context of other efforts made by educators in this direction by briefly outlining the uses of historical mathematical poems for teaching mathematics at high-school and college level. Historical Background The number e is a newcomer to the mathematical pantheon of numbers denoted by letters: it made several indirect appearances in the 17 th and 18 th centuries, and acquired its letter designation only in 1731. Our history of e starts with John Napier (1550-1617) who defined logarithms through a process called dynamical analogy [1]. Napier aimed to simplify multiplication (and in the same time also simplify division and exponentiation), by finding a model which transforms multiplication into addition. -
Finite Sum – Product Logic
Theory and Applications of Categories, Vol. 8, No. 5, pp. 63–99. FINITE SUM – PRODUCT LOGIC J.R.B. COCKETT1 AND R.A.G. SEELY2 ABSTRACT. In this paper we describe a deductive system for categories with finite products and coproducts, prove decidability of equality of morphisms via cut elimina- tion, and prove a “Whitman theorem” for the free such categories over arbitrary base categories. This result provides a nice illustration of some basic techniques in categorical proof theory, and also seems to have slipped past unproved in previous work in this field. Furthermore, it suggests a type-theoretic approach to 2–player input–output games. Introduction In the late 1960’s Lambekintroduced the notion of a “deductive system”, by which he meant the presentation of a sequent calculus for a logic as a category, whose objects were formulas of the logic, and whose arrows were (equivalence classes of) sequent deriva- tions. He noticed that “doctrines” of categories corresponded under this construction to certain logics. The classic example of this was cartesian closed categories, which could then be regarded as the “proof theory” for the ∧ – ⇒ fragment of intuitionistic propo- sitional logic. (An excellent account of this may be found in the classic monograph [Lambek–Scott 1986].) Since his original work, many categorical doctrines have been given similar analyses, but it seems one simple case has been overlooked, viz. the doctrine of categories with finite products and coproducts (without any closed structure and with- out any extra assumptions concerning distributivity of the one over the other). We began looking at this case with the thought that it would provide a nice simple introduction to some techniques in categorical proof theory, particularly the idea of rewriting systems modulo equations, which we have found useful in investigating categorical structures with two tensor products (“linearly distributive categories” [Blute et al. -
Chapter 2 of Concrete Abstractions: an Introduction to Computer
Out of print; full text available for free at http://www.gustavus.edu/+max/concrete-abstractions.html CHAPTER TWO Recursion and Induction 2.1 Recursion We have used Scheme to write procedures that describe how certain computational processes can be carried out. All the procedures we've discussed so far generate processes of a ®xed size. For example, the process generated by the procedure square always does exactly one multiplication no matter how big or how small the number we're squaring is. Similarly, the procedure pinwheel generates a process that will do exactly the same number of stack and turn operations when we use it on a basic block as it will when we use it on a huge quilt that's 128 basic blocks long and 128 basic blocks wide. Furthermore, the size of the procedure (that is, the size of the procedure's text) is a good indicator of the size of the processes it generates: Small procedures generate small processes and large procedures generate large processes. On the other hand, there are procedures of a ®xed size that generate computa- tional processes of varying sizes, depending on the values of their parameters, using a technique called recursion. To illustrate this, the following is a small, ®xed-size procedure for making paper chains that can still make chains of arbitrary lengthÐ it has a parameter n for the desired length. You'll need a bunch of long, thin strips of paper and some way of joining the ends of a strip to make a loop. You can use tape, a stapler, or if you use slitted strips of cardstock that look like this , you can just slip the slits together. -
Arxiv:1811.04966V3 [Math.NT]
Descartes’ rule of signs, Newton polygons, and polynomials over hyperfields Matthew Baker and Oliver Lorscheid Abstract. In this note, we develop a theory of multiplicities of roots for polynomials over hyperfields and use this to provide a unified and conceptual proof of both Descartes’ rule of signs and Newton’s “polygon rule”. Introduction Given a real polynomial p ∈ R[T ], Descartes’ rule of signs provides an upper bound for the number of positive (resp. negative) real roots of p in terms of the signs of the coeffi- cients of p. Specifically, the number of positive real roots of p (counting multiplicities) is bounded above by the number of sign changes in the coefficients of p(T ), and the number of negative roots is bounded above by the number of sign changes in the coefficients of p(−T ). Another classical “rule”, which is less well known to mathematicians in general but is used quite often in number theory, is Newton’s polygon rule. This rule concerns polynomi- als over fields equipped with a valuation, which is a function v : K → R ∪{∞} satisfying • v(a) = ∞ if and only if a = 0 • v(ab) = v(a) + v(b) • v(a + b) > min{v(a),v(b)}, with equality if v(a) 6= v(b) for all a,b ∈ K. An example is the p-adic valuation vp on Q, where p is a prime number, given by the formula vp(s/t) = ordp(s) − ordp(t), where ordp(n) is the maximum power of p dividing a nonzero integer n. Another example is the T -adic valuation v on k(T), for any field k, given by v ( f /g) = arXiv:1811.04966v3 [math.NT] 26 May 2020 T T ordT ( f )−ordT (g), where ordT ( f ) is the maximum power of T dividing a nonzero polyno- mial f ∈ k[T]. -
Diagrammatics in Categorification and Compositionality
Diagrammatics in Categorification and Compositionality by Dmitry Vagner Department of Mathematics Duke University Date: Approved: Ezra Miller, Supervisor Lenhard Ng Sayan Mukherjee Paul Bendich Dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Mathematics in the Graduate School of Duke University 2019 ABSTRACT Diagrammatics in Categorification and Compositionality by Dmitry Vagner Department of Mathematics Duke University Date: Approved: Ezra Miller, Supervisor Lenhard Ng Sayan Mukherjee Paul Bendich An abstract of a dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Mathematics in the Graduate School of Duke University 2019 Copyright c 2019 by Dmitry Vagner All rights reserved Abstract In the present work, I explore the theme of diagrammatics and their capacity to shed insight on two trends|categorification and compositionality|in and around contemporary category theory. The work begins with an introduction of these meta- phenomena in the context of elementary sets and maps. Towards generalizing their study to more complicated domains, we provide a self-contained treatment|from a pedagogically novel perspective that introduces almost all concepts via diagrammatic language|of the categorical machinery with which we may express the broader no- tions found in the sequel. The work then branches into two seemingly unrelated disciplines: dynamical systems and knot theory. In particular, the former research defines what it means to compose dynamical systems in a manner analogous to how one composes simple maps. The latter work concerns the categorification of the slN link invariant. In particular, we use a virtual filtration to give a more diagrammatic reconstruction of Khovanov-Rozansky homology via a smooth TQFT. -
Discussion Problems 2
CS103 Handout 11 Fall 2014 October 6, 2014 Discussion Problems 2 Problem One: Product Parities Suppose that you have n integers x₁, x₂, …, xₙ. Prove that the product x₁ · x₂ · … · xₙ is odd if and only if each number xᵢ is odd. You might want to use the following facts: the product of zero numbers is called the empty product and is, by definition, equal to 1, and any two true state- ments imply one another. Problem Two: Prime Numbers A natural number p ≥ 2 is called prime if it has no positive divisors except 1 and itself. A natural number is called composite if it is the product of two natural numbers m and n, where both m and n are greater than one. Every natural number greater than or equal to two is either prime or composite. Prove, by strong induction, that every natural number greater than or equal to two can be written as a product of prime numbers. Problem Three: Factorials! Multiplied together! The number n! is defined as 1 × 2 × … × n. We choose to define 0! = 1. Prove by induction that for any m, n ∈ ℕ, we have m!n! ≤ (m + n)!. Can you explain intuitively why this is true? Problem Four: Picking Coins Consider the following game for two players. Begin with a pile of n coins for some n ≥ 0. The first player then takes between one and ten coins out of the pile, then the second player takes between one and ten coins out of the pile. This process repeats until some player has no coins to take; at this point, that player loses the game. -
Logic and Categories As Tools for Building Theories
Logic and Categories As Tools For Building Theories Samson Abramsky Oxford University Computing Laboratory 1 Introduction My aim in this short article is to provide an impression of some of the ideas emerging at the interface of logic and computer science, in a form which I hope will be accessible to philosophers. Why is this even a good idea? Because there has been a huge interaction of logic and computer science over the past half-century which has not only played an important r^olein shaping Computer Science, but has also greatly broadened the scope and enriched the content of logic itself.1 This huge effect of Computer Science on Logic over the past five decades has several aspects: new ways of using logic, new attitudes to logic, new questions and methods. These lead to new perspectives on the question: What logic is | and should be! Our main concern is with method and attitude rather than matter; nevertheless, we shall base the general points we wish to make on a case study: Category theory. Many other examples could have been used to illustrate our theme, but this will serve to illustrate some of the points we wish to make. 2 Category Theory Category theory is a vast subject. It has enormous potential for any serious version of `formal philosophy' | and yet this has hardly been realized. We shall begin with introduction to some basic elements of category theory, focussing on the fascinating conceptual issues which arise even at the most elementary level of the subject, and then discuss some its consequences and philosophical ramifications. -
Indexed Collections Let I Be a Set (Finite of Infinite). If for Each Element
Indexed Collections Let I be a set (finite of infinite). If for each element i of I there is an associated object xi (exactly one for each i) then we say the collection xi,i∈ I is indexed by I. Each element i ∈ I is called and index and I is called the index set for this collection. The definition is quite general. Usually the set I is the set of natural numbers or positive integers, and the objects xi are numbers or sets. It is important to remember that there is no requirement for the objects associated with different elements of I to be distinct. That is, it is possible to have xi = xj when i = j. It is also important to remember that there is exactly one object associated with each index. Technically, the above corresponds to having a set X of objects and a function i : I → X. Instead of writing i(x) for element of x associated with i, instead we write xi (just different notation). Examples of indexed collections. 1. With each natural number n, associate a real number an. Then the indexed collection a0,a1,a2,... is what we usually think of as a sequence of real numbers. 2. For each positive integer i, let Ai be a set. Then we have the indexed collection of sets A1,A2,.... n Sigma notation. Let a0,a1,a2,... be a sequence of numbers. The notation i=k ai stands for the sum ak + ak+1 + ak+2 + ···an. n If k>n, then i=k ai contains no terms. -
Sums and Products
1-27-2019 Sums and Products In this section, I’ll review the notation for sums and products. Addition and multiplication are binary operations: They operate on two numbers at a time. If you want to add or multiply more than two numbers, you need to group the numbers so that you’re only adding or multiplying two at once. Addition and multiplication are associative, so it should not matter how I group the numbers when I add or multiply. Now associativity holds for three numbers at a time; for instance, for addition, a +(b + c)=(a + b)+ c. But why does this work for (say) two ways of grouping a sum of 100 numbers? It turns out that, using induction, it’s possible to prove that any two ways of grouping a sum or product of n numbers, for n 3, give the same result. ≥ Taking this for granted, I can define the sum of a list of numbers a1,a2,...an recursively as follows. A sum of a single number is just the number: { } 1 ai = a1. i=1 X I know how to add two numbers: 2 ai = a1 + a2. i=1 X To add n numbers for n> 2, I add the first n 1 of them (which I assume I already know how to do), then add the nth: − n n−1 ai = ai + an. i=1 i=1 X X Note that this is a particular way of grouping the n summands: Make one group with the first n 1, and add it to the last term. -
Grade 6 Math Circles Fall 2019 - Oct 22/23 Exponentiation
Faculty of Mathematics Centre for Education in Waterloo, Ontario Mathematics and Computing Grade 6 Math Circles Fall 2019 - Oct 22/23 Exponentiation Multiplication is often thought as repeated addition. Exercise: Evaluate the following using multiplication. 1 + 1 + 1 + 1 + 1 = 7 + 7 + 7 + 7 + 7 + 7 = 9 + 9 + 9 + 9 = Exponentiation is repeated multiplication. Exponentiation is useful in areas like: Computers, Population Increase, Business, Sales, Medicine, Earthquakes An exponent and base looks like the following: 43 The small number written above and to the right of the number is called the . The number underneath the exponent is called the . In the example, 43, the exponent is and the base is . 4 is raised to the third power. An exponent tells us to multiply the base by itself that number of times. In the example above,4 3 = 4 × 4 × 4. Once we write out the multiplication problem, we can easily evaluate the expression. Let's do this for the example we've been working with: 43 = 4 × 4 × 4 43 = 16 × 4 43 = 64 The main reason we use exponents is because it's a shorter way to write out big numbers. For example, we can express the following long expression: 2 × 2 × 2 × 2 × 2 × 2 as2 6 since 2 is being multiplied by itself 6 times. We say 2 is raised to the 6th power. 1 Exercise: Express each of the following using an exponent. 7 × 7 × 7 = 5 × 5 × 5 × 5 × 5 × 5 = 10 × 10 × 10 × 10 = 9 × 9 = 1 × 1 × 1 × 1 × 1 = 8 × 8 × 8 = Exercise: Evaluate. -
Arxiv:Math/0509655V2 [Math.CT] 26 May 2006 Nt Rdcs Aigacategory a Having Products
ON HOMOTOPY VARIETIES J. ROSICKY´ ∗ Abstract. Given an algebraic theory T , a homotopy T -algebra is a simplicial set where all equations from T hold up to homotopy. All homotopy T -algebras form a homotopy variety. We will give a characterization of homotopy varieties analogous to the character- ization of varieties. 1. Introduction Algebraic theories were introduced by F. W. Lawvere (see [31] and also [32]) in order to provide a convenient approach to study algebras in general categories. An algebraic theory is a small category T with finite products. Having a category K with finite products, a T -algebra in K is a finite product preserving functor T →K. Algebras in the category Set of sets are usual many-sorted algebras. Algebras in the category SSet of simplicial sets are called simplicial algebras and they can be also viewed as simplicial objects in the category of algebras in Set. In homotopy theory, one often needs to consider algebras up to homotopy – a homotopy T -algebra is a functor A : T → SSet such that the canonical morphism A(X1 ×···× Xn) → A(X1) ×···× A(Xn) is a weak equivalence for each finite product X1 ×···× Xn in T . These homotopy algebras have been considered in recent papers [6], [7] and [9] but the subject is much older (see, e.g., [16], [8], [35] or [38]). arXiv:math/0509655v2 [math.CT] 26 May 2006 A category is called a variety if it is equivalent to the category Alg(T ) of all T -algebras in Set for some algebraic theory T . There is a char- acterization of varieties proved by F. -
On Least Squares Exponential Sum Approximation with Positive Coefficients*
MATHEMATICS OF COMPUTATION, VOLUME 34, NUMBER 149 JANUARY 1980, PAGES 203-211 On Least Squares Exponential Sum Approximation With Positive Coefficients* By John W. Evans, William B. Gragg and Randall J. LeVeque Abstract. An algorithm is given for finding optimal least squares exponential sum approximations to sampled data subject to the constraint that the coefficients appear- ing in the exponential sum are positive. The algorithm employs the divided differences of exponentials to overcome certain problems of ill-conditioning and is suitable for data sampled at noninteger times. 1. Introduction. In this paper the following least squares approximation is con- sidered: Let y0, ...,yN be N + I real data points sampled at times 0 < t0 < • • • < tN, and let w0, ..., wN > 0 be a set of weights. For a compact subset S of the real num- bers minimize N I/ r Z ai exPi-ait„) subject only to ax, ...,ar>0 and ax, ..., ar E S and with no limitation on the number of terms r. An algorithm is given which extends that of [3], [10] so that noninteger times are acceptable. The algorithm uses the exponential [7], [9] of a certain triangular matrix [8] to obtain divided differences of the exponential function. For other work on this topic the reader is referred to [1], [2], [5] and to the references in [10]. We begin by giving some definitions and results from [3] in Section 2 and then present in Section 3 a modification of the numerical procedure of that paper which applies to approximation by positive sums of exponentials. The role of divided dif- ferences in a linear least squares step of the numerical procedure is considered in Sec- tion 4.