## ACA 2017 - Differential Algebra for an extended...

by:

I'm back from presenting work in the "23rd Conference on Applications of Computer Algebra - 2017" . It was a very interesting event. This second presentation, about "Differential algebra with mathematical functions, symbolic powers and anticommutative variables", describes a project I started working in 1997 and that is at the root of Maple's dsolve and pdsolve performance with systems of equations. It is a unique approach. Not yet emulated in any other computer algebra system.

At the end, there is a link to the presentation worksheet, with which one could open the sections and reproduce the presentation examples.

Differential algebra with mathematical functions,

symbolic powers and anticommutative variables

Edgardo S. Cheb-Terrab

Physics, Differential Equations and Mathematical Functions, Maplesoft

Abstract:
Computer algebra implementations of Differential Algebra typically require that the systems of equations to be tackled be rational in the independent and dependent variables and their partial derivatives, and of course that , everything is commutative.

It is possible, however, to extend this computational domain and apply Differential Algebra techniques to systems of equations that involve arbitrary compositions of mathematical functions (elementary or special), fractional and symbolic powers, as well as anticommutative variables and functions. This is the subject of this presentation, with examples of the implementation of these ideas in the Maple computer algebra system and its ODE and PDE solvers.

 >
 >

 >
 (1)
 >
 (2)
 >
 (3)
 >
 Differential polynomial forms for mathematical functions (basic)
 Differential polynomial forms for compositions of mathematical functions
 Generalization to many variables
 Arbitrary functions of algebraic expressions
 Examples of the use of this extension to include mathematical functions
 Differential Algebra with anticommutative variables

Edgardo S. Cheb-Terrab
Physics, Differential Equations and Mathematical Functions, Maplesoft

## ACA 2017 - Computer Algebra in High-School Educati...

by: Maple

I'm back from presenting work in the "23rd Conference on Applications of Computer Algebra - 2017" . It was a very interesting event. This first presentation, about "Active Learning in High-School Mathematics using Interactive Interfaces", describes a project I started working 23 years ago, which I believe will be part of the future in one or another form. This is work actually not related to my work at Maplesoft.

At the end, there is a link to the presentation worksheet, with which one could open the sections and reproduce the presentation examples.

Active learning in High-School mathematics using Interactive Interfaces

Edgardo S. Cheb-Terrab

Physics, Differential Equations and Mathematical Functions, Maplesoft

Abstract:

The key idea in this project is to learn through exploration using a web of user-friendly Highly Interactive Graphical Interfaces (HIGI). The HIGIs, structured as trees of interlinked windows, present concepts using a minimal amount of text while maximizing the possibility of visual and analytic exploration. These interfaces run computer algebra software in the background. Assessment tools are integrated into the learning experience within the general conceptual map, the Navigator. This Navigator offers students self-assessment tools and full access to the logical sequencing of course concepts, helping them to identify any gaps in their knowledge and to launch the corresponding learning interfaces. An interactive online set of HIGIS of this kind can be used at school, at home, in distance education, and both individually and in a group.

 Computer algebra interfaces for High-School students of "Colegio de Aplicação"  (UERJ/1994)

Motivation

When we are the average high-school student facing mathematics, we tend to feel

 • Bored, fragmentarily taking notes, listening to a teacher for 50 or more minutes
 • Anguished because we do not understand some math topics (too many gaps accumulated)
 • Powerless because we don't know what to do to understand (don't have any instant-tutor to ask questions and without being judged for having accumulated gaps)
 • Stressed by the upcoming exams where the lack of understanding may become evident

Computer algebra environments can help in addressing these issues.

 • Be as active as it can get while learning at our own pace.
 • Explore at high speed and without feeling judged. There is space for curiosity with no computational cost.
 • Possibility for making of learning a social experience.

Interactive interfaces

Interactive interfaces do not replace the teacher - human learning is an emotional process. A good teacher leading good active learning is a positive experience a student will never forget

Not every computer interface is a valuable resource, at all. It is the set of pedagogical ideas implemented that makes an interface valuable (the same happens with textbooks)

A course on high school mathematics using interactive interfaces - the Edukanet project

 – Brazilian and Canadian students/programmers were invited to participate - 7 people worked in the project.

 – Some funding provided by the Brazilian Research agency CNPq.

-Develop a framework to develop the interfaces covering the last 3 years of high school mathematics (following the main math textbook used in public schools in Brazil)

- Design documents for the interfaces according to given pedagogical guidelines.

- Create prototypes of Interactive interfaces, running Maple on background, according to design document and specified layout (allow for everybody's input/changes).

 The pedagogical guidelines for interactive interfaces

The Math-contents design documents for each chapter

 Example: complex numbers

Each math topic:  a interactive interrelated interfaces (windows)

For each topic of high-school mathematics (chapter of a textbook), develop a tree of interactive interfaces (applets) related to the topic (main) and subtopics

Example: Functions

 • Main window

 • Analysis window
 •

 • Parity window

 • Visualization of function's parity

 • Step-by-Step solution window

The Navigator: a window with a tile per math topic

 • Click the topic-tile to launch a smaller window, topic-specific, map of interrelated sub-topic tiles, that indicates the logical sequence for the sub-topics, and from where one could launch the corresponding sub-topic interactive interface.
 • This topic-specific smaller window allows for identifying the pre-requisites and gaps in understanding, launching the corresponding interfaces to fill the gaps, and tracking the level of familiarity with a topic.

 The framework to create the interfaces: a version of NetBeans on steroids ...

Complementary classroom activity on a computer algebra worksheet

This course is organized as a guided experience, 2 hours per day during five days, on learning the basics of the Maple language, and on using it to formulate algebraic computations we do with paper and pencil in high school and 1st year of undergraduate science courses.

Explore. Having success doesn't matter, using your curiosity as a compass does - things can be done in so many different ways. Have full permission to fail. Share your insights. All questions are valid even if to the side. Computer algebra can transform the learning of mathematics into interesting understanding, success and fun.

 1. Arithmetic operations and elementary functions
 2. Algebraic Expressions, Equations and Functions
 3. Limits, Derivatives, Sums, Products, Integrals, Differential Equations
 4. Algebraic manipulation: simplify, factorize, expand
 5. Matrices (Linear Algebra)

 Advanced students: guiding them to program mathematical concepts on a computer algebra worksheet

Status of the project

Prototypes of interfaces built cover:

 • Natural numbers
 • Functions
 • Integer numbers
 • Rational numbers
 • Absolute value
 • Logarithms
 • Numerical sequences
 • Trigonometry
 • Matrices
 • Determinants
 • Linear systems
 • Limits
 • Derivatives
 • Derivative of the inverse function
 • The point in Cartesian coordinates
 • The line
 • The circle
 • The ellipse
 • The parabole
 • The hyperbole
 • The conics
 More recent computer algebra frameworks: Maple Mobius for online courses and automated evaluation

Edgardo S. Cheb-Terrab
Physics, Differential Equations and Mathematical Functions, Maplesoft

## how to guess the variables?...

A. how to find xx1,xx2,xx3,yy1,yy2,yy3 that
Determinant(Matrix([[xx1,yy1,1],[xx2,yy2,1],[xx3,yy3,1]])) =(1/2)*aa*d*s*u+(1/2)*aa*d*s*a*t+(1/2)*d*v*u*t+(1/4)*d*v*a*t^2;

B. how to find x1,x2,x3,x4,y1,y2,y3,y4 that expand(
(x2 - x1)*(y4 - y3) - (y2 - y1)*(x4 - x3)) = (1/2)*d*s*aa*v+(1/2)*d*aa*v*u*t+(1/4)*d*aa*v*a*t^2+(1/2)*aa*d*s*u+(1/2)*aa*d*s*a*t+(1/2)*d*u^2*t+(3/4)*d*u*a*t^2+(1/4)*d*a^2*t^3;

## Framework for multiplication and base change in...

by: Maple

I've developed a framework in Maple for playing with cyclic division algebras. I have methods for multiplication and passing to and from:

The standard basis over the base field in terms of x^i*y^j and:
The standard matrix basis for the central simple algebra when taking coefficients in the splitting field.

I have it done in the case of degree 7, but could generalise it to any prime degree if this is of use to anyone.

## Maple T.A. Sketch Question | Randomization...

I am building an algebra 1 course for my school, and was wanting to create simple randomly generating practice sets for graphing points / lines / etc.

However, the Sketch answer type doesn't allow for any variable input like the other questions do. Is there a work around?

Presuming a randomly generated \$x and \$y, is there any way to check to see if a student has plotted the point (\$x, \$y)?

## Real government debt...

Lets say you a country where the official government debt (not adjusted for who owns the debt) is 30% of GDP. The official government debt consist of 50% government bonds and the central banks owns 40% of these government bonds. Since the government finance the centralbank we have to adjust the official government debt and remove the 40% of the government bonds that the centralbank own to get the real government debt expresed as % of GDP. In my initial calculation I simply did like this:

Real government debt expressed as % of GDP = 0.3*(1-0.4) =18%

However, that such number does not take into consideration that the official government debt is only made up of 50% government bonds. I tried to play around with different types of equations but I found none that makes any logical sense and provides me with a reasonable number. I would expect the real government debt to around 23% of GDP. This might be a simple question but I must admit I am stuck and I am not making any progress.  Any help would be appreciated.

## How can I simplify the way I write simplification ...

I'm creating a randomly generated question bank that generates the following STYLE or problem:

12x-4y2
3x6y-5

I'm currently trying to use the answer type "formula without simplification," as I'd like to avoid the students putting the questions in as the answer, and this has been driving me crazy for hours now.

I have tried the "maple" function to simplify. E.g.:

\$ANS = maple("( \$C1*( \$V1^\$A1 )*( \$V2^\$B1 ) ) / ( \$C2*( \$V1^\$A2 )*( \$V2^\$B2 ) )");

But it always throws an error.

I have simply done the math in the algorithm section, so you end up with an answer variable like this:

\$ANS = -4.0*(((z)^2.0)/(5.0*((p)^9.0)))

However, it will still count all answers submitted as incorrect.

Any help would be GREATLY appreciated =/.

Variable name clarification
I have \$C1 and \$C2, which are the constants of the numerator and denominator, respectively ("12" and "3" in the example).
I have \$V1 and \$V2 which are the first and second variable, respectively, (in the example, "x" and "y").
I have \$A1 and \$A2, which are the exponents for the variable \$V1 in the numerator and denominator, respectively.
I have \$B1 and \$B2, which are the exponents for the variable \$V2 in the numerator and denominator, respectively.

All these generate from some interesting conditions to create the problems I want (no variables named i, e, or o, for example,) but all properly initialize.

## Why does this computation hang?...

The following program hangs on the last command and a hard restart is required. The computation of a 2 x 2 matrix times a 2-vector is not that hard. Any ideas as to what is happening?

Another question: if v is a vector that depends on x and y say why does
>solve(v=0,{x,y})
not work?

It should only take a few lines of code to change v=0 to the system {components of v = 0}

## Composite number producing polynomial

Maple 13

A prime producing polynomial.

Observations on the trinomial n2 + n + 41.

by Matt C. Anderson

September 3, 2016

The story so far

We assume that n is an integer.  We focus our attention on the polynomial n^2 + n + 41.

Furthur, we analyze the behavior of the factorization of integers of the form

h(n) = n2 + n + 41                                          (expression 1)

where n is a non-negative integer.  It was shown by Legendre, in 1798 that if 0 ≤ n < 40 then h(n) is a prime number.

Certain patterns become evident when considering points (a,n) where

h(n) ≡ 0 mod a.                                             (expression 2)

The collection of all such point produces what we are calling a "graph of discrete divisors" due to certain self-similar features.  From experimental data we find that the integer points in this bifurcation graph lie on a collection of parabolic curves indexed by pairs of relatively prime integers.  The expression for the middle parabolas is –

p(r,c) = (c*x – r*y)2 – r*(c*x – r*y) – x + 41*r2.           (expression 3)

The restrictions are that 0<r<c and gcd(r,c) = 1 and all four of r,c,x, and y are integers.

Each such pair (r,c) yields (again determined experimentally and by observation of calculations) an integer polynomial a*z2 + b*z + c, and the quartic h(a*z2 + b*z + c) then factors non-trivially over the integers into two quadratic expressions.  We call this our "parabola conjecture".  Certain symmetries in the bifurcation graph are due to elementary relationships between pairs of co-prime integers.  For instance if m<n are co-prime integers, then there is an observable relationship between the parabola it determines that that formed from (n-m, n).

We conjecture that all composite values of h(n) arise by substituting integer values of z into h(a*z2 + b*z + c), where this quartic factors algebraically over Z for a*z2 + b*z + c a quadratic polynomial determined by a pair of relatively prime integers.  We name this our "no stray points conjecture" because all the points in the bifurcation graph appear to lie on a parabola.

We further conjecture that the minimum x-values for parabolas corresponding to (r, c) with gcd(r, c) = 1 are equal for fixed n.  Further, these minimum x-values line up at 163*c^2/4 where c = 2, 3, 4, ...  The numerical evidence seems to support this.  This is called our "parabolas line up" conjecture.

The notation gcd(r, c) used above is defined here.  The greatest common devisor of two integers is the smallest whole number that divides both of those integers.

Theorem 1 - Consider h(n) with n a non negative integer.

h(n) never has a factor less than 41.

We prove Theorem 1 with a modular construction.  We make a residue table with all the prime factors less than 41.  The fundamental theorem of arithmetic states that any integer greater than one is either a prime number, or can be written as a unique product of prime numbers (ignoring the order).  So if h(n) never has a prime factor less than 41, then by extension it never has an integer factor less than 41.

For example, to determine that h(n) is never divisible by 2, note the first column of the residue table.  If n is even, then h(n) is odd.  Similarly, if n is odd then h(n) is also odd.  In either case, h(n) does not have factorization by 2.

Also, for divisibility by 3, there are 3 cases to check.  They are n = 0, 1, and 2 mod 3. h(0) mod 3 is 2.  h(1) mod 3 is 1. and h(2) mod 3 is 2.  Due to these three cases, h(n) is never divisible by 3.  This is the second column of the residue table.

The number 0 is first found in the residue table for the cases h(0) mod 41 and h(40) mod 41.  This means that if n is congruent to 0 mod 41 then h(n) will be divisible by 41.  Similarly, if n is congruent to 40 mod 41 then h(n) is also divisible by 41.

After the residue table, we observe a bifurcation graph which has points when h(y) mod x is divisible by x.  The points (x,y) can be seen on the bifurcation graph.

< insert residue table here >

Thus we have shown that h(n) never has a factor less than 41.

Theorem 2

Since h(a) = a^2 + a + 41, we want to show that h(a) = h( -a -1).

Proof of Theorem 2

Because h(a) = a*(a+1) + 41,

Now h(-a -1) = (-a -1)*(-a -1 +1) + 41.

So h(-a -1) = (-a -1)*(-a) +41,

And h(-a -1) = h(a).

Which was what we wanted.

End of proof of theorem 2.

Corrolary 1

Further, if h(b) mod c ≡ = then h(c –b -1) mod c ≡ 0.

We can observe interesting patterns in the “graph of discrete divisors” on a following page.

Greetings, all!

I'm extremely new to Maple T.A., and I am building tools for my math department since I'm the only one with a programming background. I have a generic question, and sincerely apologize if I've missed it being answered elsewhere. It's a case that will probably come up multiple times for us, so I was hoping to find an answer =).

I have a problem where students are adding exponents of like bases. As an example, you get questions that look like this.

When the coefficient is 1, I'd like to accept a blank answer in the first response area as a correct solution. Is there an easy (or less easy =) way of making this happen?

## Lie Algebra to Abstract Lie algebra...

Dear All

I intend to convert Lie algebra into abstract Lie algebra with the aid of Maple packages DifferentialGeometry and Lie algebras. I want to do this for classification of Lie algebra for group inavriant solution, can anybody help me out.....?

Regards

## Optimal Lie Algebra? ...

Dear All

Is there anybody who is working on contruction of optimal Lie algebra using Maple packages like DifferentialGeometry and LieAlgebra, I tried to find commands for constructing algebra in these packages but could not find such commands. I am sure these are only package that might help me. Following is Lie algebra whose optimal system is required:

 >
 >
 (1)
 >
 (2)
 >

 >
 (2)

Regards

## Dual Quaternion Multiplication Table ...

I am trying to setup a Dual Quaternion Multiplication Table. I found the table on Wikki. I  need some help here.

Have set

x1  =1   x2 = i   x3  =j   x4   =k   x5 =e   x6 = ei   x7 = ej   x8 =ek

## Computing the ring of invariants...

I'd like to have an algorithm for computing the ring of invariants of a reductive group (i.e. G acts on V, compute C[V]^G). I know that there are algorithms in existance for this, e.g. see http://www.math.lsa.umich.edu/~hderksen/Publications/invar1999.pdf. Does anyone know if this has been implemented in Maple, or where to find code in another language? Any ideas on what sort of data structure would be appropriate

## How to calculate this resolvent?...

how to calculate Ferrari resolvent of x^4-c1*x^3+c2*x^2-c3*x+c4

 1 2 3 4 5 6 7 Last Page 1 of 17
﻿