Polynomials with Roots Modulo Every Integer 1665
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A Category-Theoretic Approach to Representation and Analysis of Inconsistency in Graph-Based Viewpoints
A Category-Theoretic Approach to Representation and Analysis of Inconsistency in Graph-Based Viewpoints by Mehrdad Sabetzadeh A thesis submitted in conformity with the requirements for the degree of Master of Science Graduate Department of Computer Science University of Toronto Copyright c 2003 by Mehrdad Sabetzadeh Abstract A Category-Theoretic Approach to Representation and Analysis of Inconsistency in Graph-Based Viewpoints Mehrdad Sabetzadeh Master of Science Graduate Department of Computer Science University of Toronto 2003 Eliciting the requirements for a proposed system typically involves different stakeholders with different expertise, responsibilities, and perspectives. This may result in inconsis- tencies between the descriptions provided by stakeholders. Viewpoints-based approaches have been proposed as a way to manage incomplete and inconsistent models gathered from multiple sources. In this thesis, we propose a category-theoretic framework for the analysis of fuzzy viewpoints. Informally, a fuzzy viewpoint is a graph in which the elements of a lattice are used to specify the amount of knowledge available about the details of nodes and edges. By defining an appropriate notion of morphism between fuzzy viewpoints, we construct categories of fuzzy viewpoints and prove that these categories are (finitely) cocomplete. We then show how colimits can be employed to merge the viewpoints and detect the inconsistencies that arise independent of any particular choice of viewpoint semantics. Taking advantage of the same category-theoretic techniques used in defining fuzzy viewpoints, we will also introduce a more general graph-based formalism that may find applications in other contexts. ii To my mother and father with love and gratitude. Acknowledgements First of all, I wish to thank my supervisor Steve Easterbrook for his guidance, support, and patience. -
Integer Linear Programs
20 ________________________________________________________________________________________________ Integer Linear Programs Many linear programming problems require certain variables to have whole number, or integer, values. Such a requirement arises naturally when the variables represent enti- ties like packages or people that can not be fractionally divided — at least, not in a mean- ingful way for the situation being modeled. Integer variables also play a role in formulat- ing equation systems that model logical conditions, as we will show later in this chapter. In some situations, the optimization techniques described in previous chapters are suf- ficient to find an integer solution. An integer optimal solution is guaranteed for certain network linear programs, as explained in Section 15.5. Even where there is no guarantee, a linear programming solver may happen to find an integer optimal solution for the par- ticular instances of a model in which you are interested. This happened in the solution of the multicommodity transportation model (Figure 4-1) for the particular data that we specified (Figure 4-2). Even if you do not obtain an integer solution from the solver, chances are good that you’ll get a solution in which most of the variables lie at integer values. Specifically, many solvers are able to return an ‘‘extreme’’ solution in which the number of variables not lying at their bounds is at most the number of constraints. If the bounds are integral, all of the variables at their bounds will have integer values; and if the rest of the data is integral, many of the remaining variables may turn out to be integers, too. -
Modular Arithmetic
CS 70 Discrete Mathematics and Probability Theory Fall 2009 Satish Rao, David Tse Note 5 Modular Arithmetic One way to think of modular arithmetic is that it limits numbers to a predefined range f0;1;:::;N ¡ 1g, and wraps around whenever you try to leave this range — like the hand of a clock (where N = 12) or the days of the week (where N = 7). Example: Calculating the day of the week. Suppose that you have mapped the sequence of days of the week (Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday) to the sequence of numbers (0;1;2;3;4;5;6) so that Sunday is 0, Monday is 1, etc. Suppose that today is Thursday (=4), and you want to calculate what day of the week will be 10 days from now. Intuitively, the answer is the remainder of 4 + 10 = 14 when divided by 7, that is, 0 —Sunday. In fact, it makes little sense to add a number like 10 in this context, you should probably find its remainder modulo 7, namely 3, and then add this to 4, to find 7, which is 0. What if we want to continue this in 10 day jumps? After 5 such jumps, we would have day 4 + 3 ¢ 5 = 19; which gives 5 modulo 7 (Friday). This example shows that in certain circumstances it makes sense to do arithmetic within the confines of a particular number (7 in this example), that is, to do arithmetic by always finding the remainder of each number modulo 7, say, and repeating this for the results, and so on. -
Modulo of a Negative Number1 1 Modular Arithmetic
Algologic Technical Report # 01/2017 Modulo of a negative number1 S. Parthasarathy [email protected] Ref.: negamodulo.tex Ver. code: 20170109e Abstract This short article discusses an enigmatic question in elementary num- ber theory { that of finding the modulo of a negative number. Is this feasible to compute ? If so, how do we compute this value ? 1 Modular arithmetic In mathematics, modular arithmetic is a system of arithmetic for integers, where numbers "wrap around" upon reaching a certain value - the modulus (plural moduli). The modern approach to modular arithmetic was developed by Carl Friedrich Gauss in his book Disquisitiones Arithmeticae, published in 1801. Modular arithmetic is a fascinating aspect of mathematics. The \modulo" operation is often called as the fifth arithmetic operation, and comes after + − ∗ and = . It has use in many practical situations, particu- larly in number theory and cryptology [1] [2]. If x and n are integers, n < x and n =6 0 , the operation \ x mod n " is the remainder we get when n divides x. In other words, (x mod n) = r if there exists some integer q such that x = q ∗ n + r 1This is a LATEX document. You can get the LATEX source of this document from [email protected]. Please mention the Reference Code, and Version code, given at the top of this document 1 When r = 0 , n is a factor of x. When n is a factor of x, we say n divides x evenly, and denote it by n j x . The modulo operation can be combined with other arithmetic operators. -
The Development and Understanding of the Concept of Quotient Group
HISTORIA MATHEMATICA 20 (1993), 68-88 The Development and Understanding of the Concept of Quotient Group JULIA NICHOLSON Merton College, Oxford University, Oxford OXI 4JD, United Kingdom This paper describes the way in which the concept of quotient group was discovered and developed during the 19th century, and examines possible reasons for this development. The contributions of seven mathematicians in particular are discussed: Galois, Betti, Jordan, Dedekind, Dyck, Frobenius, and H61der. The important link between the development of this concept and the abstraction of group theory is considered. © 1993 AcademicPress. Inc. Cet article decrit la d6couverte et le d6veloppement du concept du groupe quotient au cours du 19i~me si~cle, et examine les raisons possibles de ce d6veloppement. Les contributions de sept math6maticiens seront discut6es en particulier: Galois, Betti, Jordan, Dedekind, Dyck, Frobenius, et H61der. Le lien important entre le d6veloppement de ce concept et l'abstraction de la th6orie des groupes sera consider6e. © 1993 AcademicPress, Inc. Diese Arbeit stellt die Entdeckung beziehungsweise die Entwicklung des Begriffs der Faktorgruppe wfihrend des 19ten Jahrhunderts dar und untersucht die m/)glichen Griinde for diese Entwicklung. Die Beitrfi.ge von sieben Mathematikern werden vor allem diskutiert: Galois, Betti, Jordan, Dedekind, Dyck, Frobenius und H61der. Die wichtige Verbindung zwischen der Entwicklung dieses Begriffs und der Abstraktion der Gruppentheorie wird betrachtet. © 1993 AcademicPress. Inc. AMS subject classifications: 01A55, 20-03 KEY WORDS: quotient group, group theory, Galois theory I. INTRODUCTION Nowadays one can hardly conceive any more of a group theory without factor groups... B. L. van der Waerden, from his obituary of Otto H61der [1939] Although the concept of quotient group is now considered to be fundamental to the study of groups, it is a concept which was unknown to early group theorists. -
Grade 7/8 Math Circles Modular Arithmetic the Modulus Operator
Faculty of Mathematics Centre for Education in Waterloo, Ontario N2L 3G1 Mathematics and Computing Grade 7/8 Math Circles April 3, 2014 Modular Arithmetic The Modulus Operator The modulo operator has symbol \mod", is written as A mod N, and is read \A modulo N" or "A mod N". • A is our - what is being divided (just like in division) • N is our (the plural is ) When we divide two numbers A and N, we get a quotient and a remainder. • When we ask for A ÷ N, we look for the quotient of the division. • When we ask for A mod N, we are looking for the remainder of the division. • The remainder A mod N is always an integer between 0 and N − 1 (inclusive) Examples 1. 0 mod 4 = 0 since 0 ÷ 4 = 0 remainder 0 2. 1 mod 4 = 1 since 1 ÷ 4 = 0 remainder 1 3. 2 mod 4 = 2 since 2 ÷ 4 = 0 remainder 2 4. 3 mod 4 = 3 since 3 ÷ 4 = 0 remainder 3 5. 4 mod 4 = since 4 ÷ 4 = 1 remainder 6. 5 mod 4 = since 5 ÷ 4 = 1 remainder 7. 6 mod 4 = since 6 ÷ 4 = 1 remainder 8. 15 mod 4 = since 15 ÷ 4 = 3 remainder 9.* −15 mod 4 = since −15 ÷ 4 = −4 remainder Using a Calculator For really large numbers and/or moduli, sometimes we can use calculators to quickly find A mod N. This method only works if A ≥ 0. Example: Find 373 mod 6 1. Divide 373 by 6 ! 2. Round the number you got above down to the nearest integer ! 3. -
The Number Line Topic 1
Topic 1 The Number Line Lesson Tutorials Positive numbers are greater than 0. They can be written with or without a positive sign (+). +1 5 +20 10,000 Negative numbers are less than 0. They are written with a negative sign (−). − 1 − 5 − 20 − 10,000 Two numbers that are the same distance from 0 on a number line, but on opposite sides of 0, are called opposites. Integers Words Integers are the set of whole numbers and their opposites. Opposite Graph opposites When you sit across from your friend at Ź5 ź4 Ź3 Ź2 Ź1 0 1234 5 the lunch table, you negative integers positive integers sit opposite your friend. Zero is neither negative nor positive. Zero is its own opposite. EXAMPLE 1 Writing Positive and Negative Integers Write a positive or negative integer that represents the situation. a. A contestant gains 250 points on a game show. “Gains” indicates a number greater than 0. So, use a positive integer. +250, or 250 b. Gasoline freezes at 40 degrees below zero. “Below zero” indicates a number less than 0. So, use a negative integer. − 40 Write a positive or negative integer that represents the situation. 1. A hiker climbs 900 feet up a mountain. 2. You have a debt of $24. 3. A student loses 5 points for being late to class. 4. A savings account earns $10. 408 Additional Topics MMSCC6PE2_AT_01.inddSCC6PE2_AT_01.indd 408408 111/24/101/24/10 88:53:30:53:30 AAMM EXAMPLE 2 Graphing Integers Graph each integer and its opposite. Reading a. 3 Graph 3. -
RING THEORY 1. Ring Theory a Ring Is a Set a with Two Binary Operations
CHAPTER IV RING THEORY 1. Ring Theory A ring is a set A with two binary operations satisfying the rules given below. Usually one binary operation is denoted `+' and called \addition," and the other is denoted by juxtaposition and is called \multiplication." The rules required of these operations are: 1) A is an abelian group under the operation + (identity denoted 0 and inverse of x denoted x); 2) A is a monoid under the operation of multiplication (i.e., multiplication is associative and there− is a two-sided identity usually denoted 1); 3) the distributive laws (x + y)z = xy + xz x(y + z)=xy + xz hold for all x, y,andz A. Sometimes one does∈ not require that a ring have a multiplicative identity. The word ring may also be used for a system satisfying just conditions (1) and (3) (i.e., where the associative law for multiplication may fail and for which there is no multiplicative identity.) Lie rings are examples of non-associative rings without identities. Almost all interesting associative rings do have identities. If 1 = 0, then the ring consists of one element 0; otherwise 1 = 0. In many theorems, it is necessary to specify that rings under consideration are not trivial, i.e. that 1 6= 0, but often that hypothesis will not be stated explicitly. 6 If the multiplicative operation is commutative, we call the ring commutative. Commutative Algebra is the study of commutative rings and related structures. It is closely related to algebraic number theory and algebraic geometry. If A is a ring, an element x A is called a unit if it has a two-sided inverse y, i.e. -
Integersintegersintegers Chapter 6Chapter 6 6 Chapter 6Chapter Chapter 6Chapter Chapter 6
IntegersIntegersIntegers Chapter 6Chapter 6 Chapter 6 Chapter 6 Chapter 6 6.1 Introduction Sunita’s mother has 8 bananas. Sunita has to go for a picnic with her friends. She wants to carry 10 bananas with her. Can her mother give 10 bananas to her? She does not have enough, so she borrows 2 bananas from her neighbour to be returned later. After giving 10 bananas to Sunita, how many bananas are left with her mother? Can we say that she has zero bananas? She has no bananas with her, but has to return two to her neighbour. So when she gets some more bananas, say 6, she will return 2 and be left with 4 only. Ronald goes to the market to purchase a pen. He has only ` 12 with him but the pen costs ` 15. The shopkeeper writes ` 3 as due amount from him. He writes ` 3 in his diary to remember Ronald’s debit. But how would he remember whether ` 3 has to be given or has to be taken from Ronald? Can he express this debit by some colour or sign? Ruchika and Salma are playing a game using a number strip which is marked from 0 to 25 at equal intervals. To begin with, both of them placed a coloured token at the zero mark. Two coloured dice are placed in a bag and are taken out by them one by one. If the die is red in colour, the token is moved forward as per the number shown on throwing this die. If it is blue, the token is moved backward as per the number 2021-22 MATHEMATICS shown when this die is thrown. -
Solutions to Exercises
Solutions to Exercises Solutions for Chapter 2 Exercise 2.1 Provide a function to check if a character is alphanumeric, that is lower case, upper case or numeric. One solution is to follow the same approach as in the function isupper for each of the three possibilities and link them with the special operator \/ : isalpha c = (c >= ’A’ & c <= ’Z’) \/ (c >= ’a’ & c <= ’z’) \/ (c >= ’0’ & c <= ’9’) An second approach is to use continued relations: isalpha c = (’A’ <= c <= ’Z’) \/ (’a’ <= c <= ’z’) \/ (’0’ <= c <= ’9’) A final approach is to define the functions isupper, islower and isdigit and combine them: isalpha c = (isupper c) \/ (islower c) \/ (isdigit c) This approach shows the advantage of reusing existing simple functions to build more complex functions. 268 Solutions to Exercises 269 Exercise 2.2 What happens in the following application and why? myfst (3, (4 div 0)) The function evaluates to 3, the potential divide by zero error is ignored because Miranda only evaluates as much of its parameter as it needs. Exercise 2.3 Define a function dup which takes a single element of any type and returns a tuple with the element duplicated. The answer is just a direct translation of the specification into Miranda: dup :: * -> (*,*) dup x = (x, x) Exercise 2.4 Modify the function solomonGrundy so that Thursday and Friday may be treated with special significance. The pattern matching version is easily modified; all that is needed is to insert the extra cases somewhere before the default pattern: solomonGrundy "Monday" = "Born" solomonGrundy "Thursday" = "Ill" solomonGrundy "Friday" = "Worse" solomonGrundy "Sunday" = "Buried" solomonGrundy anyday = "Did something else" By contrast, a guarded conditional version is rather messy: solomonGrundy day = "Born", if day = "Monday" = "Ill", if day = "Thursday" = "Worse", if day = "Friday" = "Buried", if day = "Sunday" = "Did something else", otherwise Exercise 2.5 Define a function intmax which takes a number pair and returns the greater of its two components. -
Math 371 Lecture #21 §6.1: Ideals and Congruence, Part II §6.2: Quotients and Homomorphisms, Part I
Math 371 Lecture #21 x6.1: Ideals and Congruence, Part II x6.2: Quotients and Homomorphisms, Part I Why ideals? For a commutative ring R with identity, we have for a; b 2 R, that a j b if and only if (b) ⊆ (a), and u 2 R is a unit if and only if (u) = R. Having the established the notion of an ideal, we can now extend the notion of congruence to any ring with respect to any ideal. Definition. Let I be an ideal in a ring R. For a; b 2 R, we say a is congruent to b modulo I, written a ≡ b (mod I), provided that a − b 2 I. Examples. (a) For any integer k ≥ 1, we see that congruence modulo k in Z is the same thing as congruence modulo the principal ideal (k) = kZ of Z. (b) For a field F and any nonconstant polynomial p(x) in F [x], we see that congruence modulo p(x) in F [x] is the same thing as congruence modulo the principal ideal (p(x)) of F [x]. We know that the congruence in each of these examples is an equivalence relation, but is this the case for an arbitrary ideal of an arbitrary ring? Theorem 6.4. For any ideal I of a ring R, the relation of congruence modulo I is an equivalence relation. Proof. Reflexive: Since I is closed under subtraction, we have for any a 2 R that a − a = 0R 2 I; hence a ≡ a (mod I). Symmetric: For a; b 2 R, suppose that a ≡ b (mod I). -
1. Simplicity.-Let N Denote an Arbitrary Integer >0, and M an Odd of N, Aimn
160 MA THEMA TICS: E. T. BELL PROC. N. A. S. SIMPLICITY WITH RESPECT TO CERTAIN QUADRA TIC FORMS By E. T. BiLL DGPARTMUNT OF MATrHMATICS, CALUORNmA INSTITUTE OP T'CHINOIOGY Communicated December 28, 1929 1. Simplicity.-Let n denote an arbitrary integer >0, and m an odd interger >0. Write N[n = f] for the number of representations of n in the quadratic form f when this number is finite. If N[n = f] is a polynomial P(n) in the real divisors of n alone, N[n = f] is, by definition, simple; similarly for N[m = f]. In previous papers,1'23I have considered simplicity when f is a sum of an even number of squares. For an odd number > 1 of squares, no N[n = f] is simple, although if n be restricted to be a square, say k2, then N[k2 = f] is simple when f is a sum of 3, 5 or 7 squares, and for one case (k restricted) of 11 squares. To discuss simplicity for forms f in an odd number of variables, the above definition was extended in a former paper4 as follows. The exten- sion leads to theorems that are actually useful in calculations of numbers of representations, and it was devised with this end in view. Let 2 refer to all positive, zero or negative integers t which are congruent modulo M to a fixed integer T, and which render the arguments of the summand >0. Let P(n) denote a polynomial in the real divisors alone of n, and let c be a constant integer >O.