(QED) Renormalization Is a Logical Paradox, Zeta Function Regu
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Ch. 15 Power Series, Taylor Series
Ch. 15 Power Series, Taylor Series 서울대학교 조선해양공학과 서유택 2017.12 ※ 본 강의 자료는 이규열, 장범선, 노명일 교수님께서 만드신 자료를 바탕으로 일부 편집한 것입니다. Seoul National 1 Univ. 15.1 Sequences (수열), Series (급수), Convergence Tests (수렴판정) Sequences: Obtained by assigning to each positive integer n a number zn z . Term: zn z1, z 2, or z 1, z 2 , or briefly zn N . Real sequence (실수열): Sequence whose terms are real Convergence . Convergent sequence (수렴수열): Sequence that has a limit c limznn c or simply z c n . For every ε > 0, we can find N such that Convergent complex sequence |zn c | for all n N → all terms zn with n > N lie in the open disk of radius ε and center c. Divergent sequence (발산수열): Sequence that does not converge. Seoul National 2 Univ. 15.1 Sequences, Series, Convergence Tests Convergence . Convergent sequence: Sequence that has a limit c Ex. 1 Convergent and Divergent Sequences iin 11 Sequence i , , , , is convergent with limit 0. n 2 3 4 limznn c or simply z c n Sequence i n i , 1, i, 1, is divergent. n Sequence {zn} with zn = (1 + i ) is divergent. Seoul National 3 Univ. 15.1 Sequences, Series, Convergence Tests Theorem 1 Sequences of the Real and the Imaginary Parts . A sequence z1, z2, z3, … of complex numbers zn = xn + iyn converges to c = a + ib . if and only if the sequence of the real parts x1, x2, … converges to a . and the sequence of the imaginary parts y1, y2, … converges to b. Ex. -
Theorems Wednesday, May 9, 2018 12:53 AM
Theorems Wednesday, May 9, 2018 12:53 AM Theorem 1.11: Greatest-Lower-Bound Property • Suppose is an ordered set with the least-upper-bound property • Suppose , and is bounded below • Let be the set of lower bounds of • Then exists in and Theorem 1.20: The Archimedean property of • Given , and • There is a positive integer such that Theorem 1.20: is dense in • If , and , then there exists a s.t. • We can always find a rational number between two real numbers Theorem 1.21: -th Root of Real Numbers • For every real , and positive integer • There is one and only one positive real number s.t. • Theorem 1.31: Properties of Complex Numbers • If and are complex numbers, then • • • • is real and positive (except when ) Theorem 1.33: Properties of Complex Numbers • If and are complex numbers, then • unless in which case • • • • (Triangle Inequality) Theorem 1.37: Properties of Euclidean Spaces • Suppose , then • Page 1 • if and only if • • (Schwarz's Inequality) • (Triangle Inequality) • (Triangle Inequality) Theorem 2.8: Infinite Subset of Countable Set • Every infinite subset of a countable set is countable Theorem 2.12: Union of Countable Sets • Let be a sequence of countable sets, then • Theorem 2.13: Cartesian Product of Countable Sets • Let be a countable set • Let be the set of all -tuples where ○ for ○ may not be distinct • Then is countable Theorem 2.14: Cantor's Diagonalization Argument • Let be the set of all sequqnecse whose digits are 0 and 1 • Then is uncountable Theorem 2.19: Every Neighborhood is an Open Set • Every neighborhood -
Arxiv:1207.1472V2 [Math.CV]
SOME SIMPLIFICATIONS IN THE PRESENTATIONS OF COMPLEX POWER SERIES AND UNORDERED SUMS OSWALDO RIO BRANCO DE OLIVEIRA Abstract. This text provides very easy and short proofs of some basic prop- erties of complex power series (addition, subtraction, multiplication, division, rearrangement, composition, differentiation, uniqueness, Taylor’s series, Prin- ciple of Identity, Principle of Isolated Zeros, and Binomial Series). This is done by simplifying the usual presentation of unordered sums of a (countable) family of complex numbers. All the proofs avoid formal power series, double series, iterated series, partial series, asymptotic arguments, complex integra- tion theory, and uniform continuity. The use of function continuity as well as epsilons and deltas is kept to a mininum. Mathematics Subject Classification: 30B10, 40B05, 40C15, 40-01, 97I30, 97I80 Key words and phrases: Power Series, Multiple Sequences, Series, Summability, Complex Analysis, Functions of a Complex Variable. Contents 1. Introduction 1 2. Preliminaries 2 3. Absolutely Convergent Series and Commutativity 3 4. Unordered Countable Sums and Commutativity 5 5. Unordered Countable Sums and Associativity. 9 6. Sum of a Double Sequence and The Cauchy Product 10 7. Power Series - Algebraic Properties 11 8. Power Series - Analytic Properties 14 References 17 arXiv:1207.1472v2 [math.CV] 27 Jul 2012 1. Introduction The objective of this work is to provide a simplification of the theory of un- ordered sums of a family of complex numbers (in particular, for a countable family of complex numbers) as well as very easy proofs of basic operations and properties concerning complex power series, such as addition, scalar multiplication, multipli- cation, division, rearrangement, composition, differentiation (see Apostol [2] and Vyborny [21]), Taylor’s formula, principle of isolated zeros, uniqueness, principle of identity, and binomial series. -
INFINITE SERIES in P-ADIC FIELDS
INFINITE SERIES IN p-ADIC FIELDS KEITH CONRAD 1. Introduction One of the major topics in a course on real analysis is the representation of functions as power series X n anx ; n≥0 where the coefficients an are real numbers and the variable x belongs to R. In these notes we will develop the theory of power series over complete nonarchimedean fields. Let K be a field that is complete with respect to a nontrivial nonarchimedean absolute value j · j, such as Qp with its absolute value j · jp. We will look at power series over K (that is, with coefficients in K) and a variable x coming from K. Such series share some properties in common with real power series: (1) There is a radius of convergence R (a nonnegative real number, or 1), for which there is convergence at x 2 K when jxj < R and not when jxj > R. (2) A power series is uniformly continuous on each closed disc (of positive radius) where it converges. (3) A power series can be differentiated termwise in its disc of convergence. There are also some contrasts: (1) The convergence of a power series at its radius of convergence R does not exhibit mixed behavior: it is either convergent at all x with jxj = R or not convergent at P n all x with jxj = R, unlike n≥1 x =n on R, where R = 1 and there is convergence at x = −1 but not at x = 1. (2) A power series can be expanded around a new point in its disc of convergence and the new series has exactly the same disc of convergence as the original series. -
The Infinity Theorem Is Presented Stating That There Is at Least One Multivalued Series That Diverge to Infinity and Converge to Infinite Finite Values
Open Journal of Mathematics and Physics | Volume 2, Article 75, 2020 | ISSN: 2674-5747 https://doi.org/10.31219/osf.io/9zm6b | published: 4 Feb 2020 | https://ojmp.wordpress.com CX [microresearch] Diamond Open Access The infinity theorem Open Mathematics Collaboration∗† March 19, 2020 Abstract The infinity theorem is presented stating that there is at least one multivalued series that diverge to infinity and converge to infinite finite values. keywords: multivalued series, infinity theorem, infinite Introduction 1. 1, 2, 3, ..., ∞ 2. N =x{ N 1, 2,∞3,}... ∞ > ∈ = { } The infinity theorem 3. Theorem: There exists at least one divergent series that diverge to infinity and converge to infinite finite values. ∗All authors with their affiliations appear at the end of this paper. †Corresponding author: [email protected] | Join the Open Mathematics Collaboration 1 Proof 1 4. S 1 1 1 1 1 1 ... 2 [1] = − + − + − + = (a) 5. Sn 1 1 1 ... 1 has n terms. 6. S = lim+n + S+n + 7. A+ft=er app→ly∞ing the limit in (6), we have S 1 1 1 ... + 8. From (4) and (7), S S 2 = 0 + 2 + 0 + 2 ... 1 + 9. S 2 2 1 1 1 .+.. = + + + + + + 1 10. Fro+m (=7) (and+ (9+), S+ )2 2S . + +1 11. Using (6) in (10), limn+ =Sn 2 2 limn Sn. 1 →∞ →∞ 12. limn Sn 2 + = →∞ 1 13. From (6) a=nd (12), S 2. + 1 14. From (7) and (13), S = 1 1 1 ... 2. + = + + + = (b) 15. S 1 1 1 1 1 ... + 1 16. S =0 +1 +1 +1 +1 +1 1 .. -
Mathematics Course: Analysis I
Analysis I Carl Turner November 21, 2010 Abstract These are notes for an undergraduate course on analysis; please send corrections, suggestions and notes to [email protected] The author's homepage for all courses may be found on his website at SuchIdeas.com, which is where updated and corrected versions of these notes can also be found. The course materials are licensed under a permissive Creative Commons license: Attribution- NonCommercial-ShareAlike 3.0 Unported (see the CC website for more details). Thanks go to Professor G. Paternain for allowing me to use his Analysis I course (Lent 2010) as the basis for these notes. Contents 1 Limits and Convergence3 1.1 Fundamental Properties of the Real Line...........................3 1.2 Cauchy Sequences.......................................5 1.3 Series..............................................6 1.4 Sequences of Non-Negative Terms...............................7 1.5 Alternating Series and Absolute Convergence........................ 10 2 Continuity 13 2.1 Denitions and Basic Properties............................... 13 2.2 Intermediate Values, Extreme Values and Inverses..................... 15 3 Dierentiability 18 3.1 Denitions and Basic Properties............................... 18 3.2 The Mean Value Theorem and Taylor's Theorem...................... 20 3.3 Taylor Series and Binomial Series............................... 25 3.4 * Comments on Complex Dierentiability.......................... 26 4 Power Series 28 4.1 Fundamental Properties.................................... 28 4.2 Standard Functions....................................... 32 4.2.1 Exponentials and logarithms............................. 32 1 4.2.2 Trigonometric functions................................ 35 4.2.3 Hyperbolic functions.................................. 37 5 Integration 38 5.1 Denitions and Key Properties................................ 38 5.2 Computation of Integrals................................... 44 5.3 Mean Values and Taylor's Theorem Again, Improper Integrals and the Integral Test. -
Series: Convergence and Divergence Comparison Tests
Series: Convergence and Divergence Here is a compilation of what we have done so far (up to the end of October) in terms of convergence and divergence. • Series that we know about: P∞ n Geometric Series: A geometric series is a series of the form n=0 ar . The series converges if |r| < 1 and 1 a1 diverges otherwise . If |r| < 1, the sum of the entire series is 1−r where a is the first term of the series and r is the common ratio. P∞ 1 2 p-Series Test: The series n=1 np converges if p1 and diverges otherwise . P∞ • Nth Term Test for Divergence: If limn→∞ an 6= 0, then the series n=1 an diverges. Note: If limn→∞ an = 0 we know nothing. It is possible that the series converges but it is possible that the series diverges. Comparison Tests: P∞ • Direct Comparison Test: If a series n=1 an has all positive terms, and all of its terms are eventually bigger than those in a series that is known to be divergent, then it is also divergent. The reverse is also true–if all the terms are eventually smaller than those of some convergent series, then the series is convergent. P P P That is, if an, bn and cn are all series with positive terms and an ≤ bn ≤ cn for all n sufficiently large, then P P if cn converges, then bn does as well P P if an diverges, then bn does as well. (This is a good test to use with rational functions. -
Divergent and Conditionally Convergent Series Whose Product Is Absolutely Convergent
DIVERGENTAND CONDITIONALLY CONVERGENT SERIES WHOSEPRODUCT IS ABSOLUTELYCONVERGENT* BY FLORIAN CAJOKI § 1. Introduction. It has been shown by Abel that, if the product : 71—« I(¥» + V«-i + ■•• + M„«o)> 71=0 of two conditionally convergent series : 71—0 71— 0 is convergent, it converges to the product of their sums. Tests of the conver- gence of the product of conditionally convergent series have been worked out by A. Pringsheim,| A. Voss,J and myself.§ There exist certain conditionally- convergent series which yield a convergent result when they are raised to a cer- tain positive integral power, but which yield a divergent result when they are raised to a higher power. Thus, 71 = «3 Z(-l)"+13, 7>=i n where r = 7/9, is a conditionally convergent series whose fourth power is con- vergent, but whose fifth power is divergent. || These instances of conditionally * Presented to the Society April 28, 1900. Received for publication April 28, 1900. fMathematische Annalen, vol. 21 (1883), p. 327 ; vol. 2(5 (1886), p. 157. %Mathematische Annalen, vol. 24 (1884), p. 42. § American Journal of Mathematics, vol. 15 (1893), p. 339 ; vol. 18 (1896), p. 195 ; Bulletin of the American Mathematical Society, (2) vol. 1 (1895), p. 180. || This may be a convenient place to point out a slight and obvious extension of the results which I have published in the American Journal of Mathematics, vol. 18, p. 201. It was proved there that the conditionally convergent series : V(_l)M-lI (0<r5|>). Sí n when raised by Cauchy's multiplication rule to a positive integral power g , is convergent whenever (î — l)/ï <C r ! out the power of the series is divergent, if (q— 1 )¡q > r. -
Dirichlet’S Test
4. CONDITIONALLY CONVERGENT SERIES 23 4. Conditionally convergent series Here basic tests capable of detecting conditional convergence are studied. 4.1. Dirichlet’s test. Theorem 4.1. (Dirichlet’s test) n Let a complex sequence {An}, An = k=1 ak, be bounded, and the real sequence {bn} is decreasing monotonically, b1 ≥ b2 ≥ b3 ≥··· , so that P limn→∞ bn = 0. Then the series anbn converges. A proof is based on the identity:P m m m m−1 anbn = (An − An−1)bn = Anbn − Anbn+1 n=k n=k n=k n=k−1 X X X X m−1 = An(bn − bn+1)+ Akbk − Am−1bm n=k X Since {An} is bounded, there is a number M such that |An|≤ M for all n. Therefore it follows from the above identity and non-negativity and monotonicity of bn that m m−1 anbn ≤ An(bn − bn+1) + |Akbk| + |Am−1bm| n=k n=k X X m−1 ≤ M (bn − bn+1)+ bk + bm n=k ! X ≤ 2Mbk By the hypothesis, bk → 0 as k → ∞. Therefore the right side of the above inequality can be made arbitrary small for all sufficiently large k and m ≥ k. By the Cauchy criterion the series in question converges. This completes the proof. Example. By the root test, the series ∞ zn n n=1 X converges absolutely in the disk |z| < 1 in the complex plane. Let us investigate the convergence on the boundary of the disk. Put z = eiθ 24 1. THE THEORY OF CONVERGENCE ikθ so that ak = e and bn = 1/n → 0 monotonically as n →∞. -
1 Notes for Expansions/Series and Differential Equations in the Last
Notes for Expansions/Series and Differential Equations In the last discussion, we considered perturbation methods for constructing solutions/roots of algebraic equations. Three types of problems were illustrated starting from the simplest: regular (straightforward) expansions, non-uniform expansions requiring modification to the process through inner and outer expansions, and singular perturbations. Before proceeding further, we first more clearly define the various types of expansions of functions of variables. 1. Convergent and Divergent Expansions/Series Consider a series, which is the sum of the terms of a sequence of numbers. Given a sequence {a1,a2,a3,a4,a5,....,an..} , the nth partial sum Sn is the sum of the first n terms of the sequence, that is, n Sn = ak . (1) k =1 A series is convergent if the sequence of its partial sums {S1,S2,S3,....,Sn..} converges. In a more formal language, a series converges if there exists a limit such that for any arbitrarily small positive number ε>0, there is a large integer N such that for all n ≥ N , ^ Sn − ≤ ε . (2) A sequence that is not convergent is said to be divergent. Examples of convergent and divergent series: • The reciprocals of powers of 2 produce a convergent series: 1 1 1 1 1 1 + + + + + + ......... = 2 . (3) 1 2 4 8 16 32 • The reciprocals of positive integers produce a divergent series: 1 1 1 1 1 1 + + + + + + ......... (4) 1 2 3 4 5 6 • Alternating the signs of the reciprocals of positive integers produces a convergent series: 1 1 1 1 1 1 − + − + − + ......... = ln 2 . -
Chapter 3: Infinite Series
Chapter 3: Infinite series Introduction Definition: Let (an : n ∈ N) be a sequence. For each n ∈ N, we define the nth partial sum of (an : n ∈ N) to be: sn := a1 + a2 + . an. By the series generated by (an : n ∈ N) we mean the sequence (sn : n ∈ N) of partial sums of (an : n ∈ N) (ie: a series is a sequence). We say that the series (sn : n ∈ N) generated by a sequence (an : n ∈ N) is convergent if the sequence (sn : n ∈ N) of partial sums converges. If the series (sn : n ∈ N) is convergent then we call its limit the sum of the series and we write: P∞ lim sn = an. In detail: n→∞ n=1 s1 = a1 s2 = a1 + a + 2 = s1 + a2 s3 = a + 1 + a + 2 + a3 = s2 + a3 ... = ... sn = a + 1 + ... + an = sn−1 + an. Definition: A series that is not convergent is called divergent, ie: each series is ei- P∞ ther convergent or divergent. It has become traditional to use the notation n=1 an to represent both the series (sn : n ∈ N) generated by the sequence (an : n ∈ N) and the sum limn→∞ sn. However, this ambiguity in the notation should not lead to any confu- sion, provided that it is always made clear that the convergence of the series must be established. Important: Although traditionally series have been (and still are) represented by expres- P∞ sions such as n=1 an they are, technically, sequences of partial sums. So if somebody comes up to you in a supermarket and asks you what a series is - you answer “it is a P∞ sequence of partial sums” not “it is an expression of the form: n=1 an.” n−1 Example: (1) For 0 < r < ∞, we may define the sequence (an : n ∈ N) by, an := r for each n ∈ N. -
1 X = 1 Ln 2 Ln 2
Let’s consider that power series for ln x about x 1 x12 x 1 3 x 1 4 x 1 5 x 1 6 x 1 7 x 1 8 lnxx 1 ... 2 3 4 5 6 7 8 So if this is true, then what is ln2 ? 212 21 3 21 4 21 5 21 6 21 7 21 8 ln2 2 1 ... 2 3 4 5 6 7 8 12 1 3 1 4 1 5 1 6 1 7 1 8 ln2 1 ... 2 3 4 5 6 7 8 n1 1 1 1 1 1 1 1 1 ln2 1 ... ... = the alternating harmonic series! 2 3 4 5 6 7 8 n This series is Conditionally Convergent since the non-alternating harmonic series diverges (by integral test), but the alternating series converges (by alternating series test). Now we know that the alternating harmonic series converges to . We can also show that this series converges when 02x . 111111111111111 So ln2 1 ... 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Let’s rearrange these terms: 1111111111111111 ln2 1 ... 2 4 3 6 8 5 10 12 7 14 16 9 18 20 11 22 Do you agree that this series will include all of the terms of the power series for ? Let’s group certain terms together: 1111111111 111 1 11 ln2 1 ... 2 4 3 6 8 5 10 12 7 14 16 9 18 20 11 22 11111111111 = ... 2 4 6 8 10 12 14 16 18 20 22 Look at each term in this series, compared with each term in our original series for ln2.