Showing posts with label math. Show all posts
Showing posts with label math. Show all posts

Sunday, November 16, 2025

Thinking Better: The Art of the Shortcut in Math and Life

Thinking Better: The Art of the Shortcut in Math and Life by Marcus Du Sautoy

Math relies on building blocks and shortcuts to help quickly get to conclusions. Multiplication is a fast way of doing repeated addition. Exponents are just repeated multiplication and good by done by repeating additional over and over. However, shortcuts enable doing these in simpler fashion. More advanced math like calculus are essentially just shortcuts to solve certain types of problems. There are many shortcuts that can be found in math. Spotting patterns and shortcuts can help quickly resolve problems. Likewise, in life there are many shortcuts that can be found to quickly come to an accurate conclusion. However, like math, there are also some things that require doing things the "hard way", like practicing an instrument.

Sunday, March 02, 2025

Gödel, Escher, Bach: An Eternal Golden Braid

Gödel, Escher, Bach: An Eternal Golden Braid by Douglas R Hofstadter

How could you resist a math book that name drops a great composer and artist in the title? The book ties together the works of the two brilliantly with the Gödel's incompleteness theorem. Examples abound of self-referencing or self-continuing systems. Escher has drawings that seem to extend up endlessly. Bach has compositions that go up only to be back where they started. 

Alas, the book is incredibly verbose. The preface to the 20th Anniversary edition goes on for more than 20 pages. The book itself extends beyond 700 pages. The chapters are mostly in couplets, with the first being a conversation between Tortoise and Achilles, followed by a chapter containing detailed analysis. The author was inspired by Lewis Carroll in approach, but not in succinctness. By the end, I was speed skimming. Perhaps I should have just read the outline at the start. The only problem with that would be missing out on the various drawings (primarily from Escher) included. The author did mention that he started out writing a paper and then transformed it into a book. It would have been nice to see that paper.

The first part of the book talks about incompleteness and systems that return on themselves or require themselves for definition. It elaborates that ad nauseum, and then focuses more on artificial intelligence. The view of machine learning and artificial intelligence from a 45 years ago is much different than today.  At that time approaching human capabilities was seen as fairly impossible. Things are much closer now. The approach has also changed. Rather than try to create detailed decision trees, today most machine learning is done from models and training. AI "learns" and helps program itself. The book can be an interesting reference on the history of artificial intelligence and how things have changed in the past decades.


Tuesday, October 22, 2024

Graph Theory: A Problem Oriented Approach

Graph Theory: A Problem Oriented Approach by Daniel A. Marcus

This is a quick introduction to graph theory loaded with problems. You can quickly read the text content in under an hour. However, the main goal is to work through the problems to understand and prove many of the basic concepts of graph theory. There are bits of "practical" application combined in the introduction to graph theory.

Sunday, September 29, 2024

Number: The Language of Science

Number: The Language of Science by tobias dantzig

Numbers are a basic part of our lives today. Where did they come from? This book was originally written almost a century ago. However, many of the topics covered date back millenia. Numbers and language evolved and became more complex. While people have some innate number sense, the adoption of linguistic numbers was a significant breakthrough. We still use base-10 today because we have 10 fingers. Concepts like 0 and the use of algebraic variables had a significant impact on the use of numbers, but didn't come into place until much later. Rational, irrational and imaginary numbers came about only after significant work. Infinity was an interesting concept that took a while to come about. Primes and other components also played a key role and gradually came about. Many of the basic concepts we think of today were centuries in the making.

Wednesday, July 05, 2023

Weapons of Math Destruction: How Big Data Increases Inequality and Threatens Democracy

Big data has the potential to erase past prejudices and provide an equal playing field for everybody. Rather than rely on biased feelings, computers can look just at the numbers to make objective decisions. This could allow previously redlined groups better access to loans and money. It could help with hiring and termination of employees. It could also better target resources to improve education and reduce crime. Big data could also help companies make a lot of money.

Alas, in the real world things have not quite turned out that way. The one area where big data has had the most success is in earning companies a lot of money. However, this has been fraught with significant negativity.  At its worst, big data may make totally erroneous predictions based on limited or erroneous data. It can be very difficult to appeal these decisions. At other times, the models serve to ingrain past prejudices in seemingly objective ways.

A good big data model needs a continuous feedback loop to improve predictions and improve the results. It relies on good data. It also must have data that is meaningful and well collected. A grading of teachers by improved student test scores may seem objective, but it is easily manipulated. If there was cheating the previous year, the improvement would be lower. The single data point could also be subject to isolated factors (such as sick students on testing day.)

Bucketing people into groups may make analysis more simple, but it could also produce misleading results for individuals. Using proxies can also have problems. Some data may be easier to collect than what is attempted to be measured, but does not provide the same result.

Data also has the challenge that it can lead to unintended changes in behavior. This is especially problematic when proxies are used. Instead of showing an improvement in the desired behavior, the model encourages changes in the proxy. Data may also be fudged or the model tweaked to get a desired result. The "objective" analysis is merely an insulating layer between subjectiveness.

Big data is a tool. It can help humans uncover hidden gems. However, it can also lead to bad subjectivity in the name of objectivity. It is important to understand the details before relying on data to make decisions.

Monday, January 30, 2023

The Art of Statistics: How to Learn from Data

Statistics can be powerful, but also mystical. This book attempts to take the mystery out by building up knowledge from the ground up. Statistical topics are developed using real world applications and then analyzed from a "brute force" method. Then the math is applied as an "easy solution" to the problems. The author also pull from his experience using statistics in various cases. One that is covered multiple times is the doctor that had killed is patients. Naive statistical analysis could have caught him. However, it would also have caught innocent doctors. It is important to do more thorough statistical analysis as well as look at the real world conditions. The book concludes with an analysis of statistics and the state of scientific research. P-values have been taken as gospel and many "tricks" have been used by researchers to get publishable results, even if these are not really meaningful.

Thursday, January 26, 2023

Naked Statistics: Stripping the Dread from the Data

Statistics can be a source of much confusion. I recent newspaper article stated "only [small number]% of coaches are women, yet [large number] girls play this sport." The goal was to saw there is a great shortage of female coaches. But using a percentage in one place and number in another is misleading. "Just 5% of coaches are female, while 5,000,000 girls play this sport" sounds really bad. But if there are also 500,000,000 boys that play the sport, it actually shows female coaches are over-represented. Numbers and statistics are a great way to tell these "lies".

The author initially shied away from "math heavy" classes. Abstract ideas did not appeal to him. However, once he was able to connect concrete interests it became much more appealing. In this book he tries to impart that feeling with a lighthearted look at the practical nature of statistics.

Statistics can be used to help infer important conclusions. They can also be used to come up with many false explanations. Knowing the difference can be challenging. The sampling method, the data, the methodology and the questions asked can all play a role in the quality. It is very easy to come up with "accurate" statistics that are totally wrong. We have a duty to find these and understand them. This book is a helpful, easy to understand primer.

Sunday, July 24, 2022

Innumeracy: Mathematical Illiteracy and Its Consequences

People are generally bad with numbers. They can make simple logical mistake with numbers. This book calls out of a few of the more common "math errors" that people make and see. Smart people can take advantage of this lake of numerical skill and play odds to their benefit. 

Part of the problem with math is education. Elementary education does not typically attract people that are good at math. We thus end up with math education taught by those that never really learned it well. College professors tend to be off in their erudite world. Perhaps we need to swap out the elementary school math teachers with college profs to help everryone.

Saturday, July 09, 2022

A Tour of the Calculus

A Tour of the Calculus attempts to explore Calculus from a practical, evolutionary point of view. What can we do with it? What is useful. There are many conversational pieces as the author "talks" with some of the key contributors to modern math and learns what they have done and why. It tries to be conversational, but does resort to a bit of mathematical notation. It almost worked for me. While I did get many key insights into Calculus, I found it got just a bit too much into the details to keep me from being able to focus on the general narrative. 

Monday, October 25, 2021

Humble Pi: When Math Goes Wrong in the Real World

Humble Pi is a fun book about math gone bad. Or perhaps smore accurately, it is about humans' poor understanding of numbers. There are big disasters and little flubs described. Bridges collapsed because minor changes greatly increased loads. McDonald's went to court because they seemingly exaggerated the number of meal combinations. Other companies understated the number of combinations. People have been given lethal doses of medications due to misunderstandings of the unit of measurements. The Gimli Glider was a 767 airplane that ran out of fuel midflight. Luckily, the pilot was able to glide it down to a landing. A number of things together created the issue. However, a key issue was the use of wrong units for fuel calculations.

People can sometimes have very bad logic when confronted with big numbers. One meme mistakenly assumed dividing a large number in the millions by another in the millions would have an answer in the millions. There have been internet flame wars over whether a week has 7 or 8 days. (Having something 0-based or 1-based does make a big difference.) 

The intersection of computers and people also create all sorts of problems. In one hilarious case, the upgrade of a an operating system (and downgrade of mail software) resulted in emails only being able to reach recipients within 500 miles. (Thank you speed of light!) Strange results often appear due to the binary representation of numbers. Results that exceed the maximum capacity can be very unpredictable. (When the 8-bit level number in pac-man rolled over, things went bezerk.) However, a similar overrun has also lead to a rocket to crash. (Legacy code also contributed to this. The part that caused the self-destruct did not even need to be run at the time.)

People's inability to behave like "math" can also help finding frauds. A professor can distinguish between those that really did record a large number of coin flips and those that made things up. Those that really did it are more likely to have some longer "runs" than a faker would appear. Forensic accounting can also be used to identify fraud due to bad distributions of numbers, indicating more likely "fakes".

What do we learn from all this? People can make bad mistakes with numbers. However, there are also many cases of bad number usage that we are still living with. There are also plenty of others that have been identified by the perpetrators, but have been "swept under the rug" as trade secrets.

Tuesday, May 04, 2021

In Pursuit of the Traveling Salesman: Mathematics at the Limits of Computation

The traveling salesman problem is a popular computation problem that has evaded a simple solution. The goal is to travel from one point through a number of different points just once and eventually return to the starting point. There are practical applications in route planning as well as many other areas. However, the solution has evaded a simple solution. The brute force solution grows exponentially as more points are added. Some heuristics can be used to help get a "good" solution and then iterate on it until it becomes optimal.

In Pursuit of the Traveling Salesman attempts to be accessible, with a great deal of the text focussed on the history and the people involved. However, it also delves deep into the math. I found myself lost with some of the numbers and optimal solutions. Why are these numbers getting bigger? How are we sure this is the optimal solution. These may have been explained earlier, but I had lost it.

Luckily, the focus is primarily on the people. Even if you get lost with the math, you can follow along with the people. Of key importance is the concept of Linear Programming introduced by George Dantzig. (He had a somewhat auspicious start, solving some "unsolved" statistics problems that he thought were homework.) I got a general idea about how linear programming worked from the text, but it does not really attempt to be a tutorial.

The end of the book presents a number of interesting uses and attempts to solve the traveling salesman problem. Some researchers have used animals grabbing food. Others have attempted to use DNA. People can do a pretty good job with a small set. However, with big sets, they bog down. Some really complex problems involve attempting to trace paths on famous paintings.

The big mystery is still P=NP. Is the salesman problem a difficult problem without an easy solution? Or is there a way that anything can be solved in a reasonable time? There is still a million dollar reward out there, so we may find out.

Saturday, April 24, 2021

Introduction to Graph Theory (Dover Books on Mathematics)

I think I liked the original title, Dots and Lines, better. However, Introduction to Graph Theory was what I was searching for. This book is getting close to 50 years old. However, the basics of graph theory still remain. Perhaps the only part that caught me off guard was the mention that the 4-color problem had not been proved. Alas, when I got to the end, the author corrected this with mention of the proof. (It came out right around the time this book was published.) 

The book targets a more general audience than just mathematicians. However, it does not skimp on rigor. The opening chapter starts with an introduction to "pure mathematics". The author desires that we can find the joy in math that mathematicians find, and not get bogged down with mechanics.  There are plenty of detailed proofs and exercises in the book. At times the book gets pretty deep into the nitty-gritty. However, it will often then bounce back out to more easily acceptable prose. I found it to be a good introduction to graph theory. It contained enough detail to fill in basic understanding gaps and seems to have a good chunk of problems to go through on a re-read.

Saturday, April 10, 2021

The Fascinating World of Graph Theory

The Fascinating World of Graph Theory is an introduction to graph theory that focuses on the interesting puzzles and participants in historical context. It introduces core concepts in graph theory as they are needed to tell the story. In doing so, it also provides the biographical history of the mathematicians that were involved in identifying and solving the problems. It is not quite an "introduction" to graph theory, though it does cover basic concepts. A deep math background is not required to start the book. However, the mathematical details and proof due appear. They can be understood in the context of the book (though I did have to occasionally go back to recall what a certain symbol meant.) I did enjoy reading the brief histories of the problems. These were interspersed with the math. There are plenty of problems that could help this be a "math textbook", while there is also historical information for a "general history of science". However, it doesn't quite fit into either category and instead rests somewhere in between.

Wednesday, December 02, 2020

The Joy of x: A Guided Tour of Math, from One to Infinity

The Joy of x attempts to demystify math so that "the rest of us" can gain some of the excitement that mathematicians do. The author succeeds fairly well in relating complex mathematics to the real world.

The Joy of x starts simple and takes nothing for granted. An example from Sesame Street calling for "fish fish fish" begins the introduction into numbers and counting. Subtraction begat the need for negative numbers. Square roots gave us the need for imaginary and complex numbers. Parabolas and other conic shapes have the ability to concentrate and amplify due to their structure. Geometry, calculus and algebra all help us explain real world phenomena.

"School math" often focuses on isolated equations or contrived story problem. Connecting it to the real world does a good job of making things alive. There are always the assumptions in word problems that we are asked to take to solve them. In high school, wind resistance always drove me crazy. Riding my bicycle, I knew that the wind and hills made a huge difference in speed and effort. Yet, all word problems seems to assume that all travel was done in a flat vacuum. The math to account for those details was "too complex" for the moment, but important for the real world. Even acknowledging those factors helps increase the "joy" in math.

Tuesday, October 06, 2020

The Math Myth: And Other STEM Delusions

Despite the title, the Math Myth is actually pro math. However, it enunciates many concerns with the way that math is taught and used as a "weed out". Most students are required to take standard math classes. These classes are often taught by adjunct professors, because the full professor do not want to teach them. This leaves most students exposed to mediocre math instruction and has also led to a decline in those studying math. The courses have also "weeded out" many students who would otherwise be able to complete degrees.

Math is critically import to society today. Calculus underpins much of our advanced technology. Due to complex mathematical calculations, we have airplanes, microchips, cell phones and most things we take for granted today. However, only a very small number of people are actually using the advanced math in their work. Even in the development of advanced technology, there may be only a handful of people that need to know math beyond basic algebra. And even for this math, people are rarely solving them "the way they did in school." Most of the work is done by a computer. 

What can be done? Practical math and arithmetic can be stressed in school. There is a need to understand basic financial transactions as well as other things that are encountered in daily life. Statistics is also highly valuable. Advanced math has its place, but an emphasis should be on understanding rather than solving equations that a computer could solve. The advanced math should also be made more appropriate to the study. Why not have a math course taught by a psychologist? If psychologists need math, a psychologist may be better able to teach the practical math than a mathematician. Courses in math related courses (such as statistics) may be much more valuable for some fields of study. Math should not prevent students from entering their careers.

Sunday, April 05, 2020

Infinite Powers

Infinite Powers explores the evolution of calculus and the important roll that it plays in our lives. Both the concepts of "0" and "infinity" are key to the understanding of the world. However, these were not universally understood concepts in the ancient world. Many mathematicians did understand bits of it, but it wasn't until Newton and Leibniz separately put it all together.
Curves had made things difficult for ancient mathematicians. Calculating the area of a circle just didn't come up with a rational number. Different approaches were used to try to calculate the area (such as making many-sided polygons on the inside and out. However, it took the insight of "subdividing" into infinite strips to really come with a conclusion.
Today the approximations and insights from calculus are used extensively in our world. The radio waves we use for communications and the 3d modelling in digital animation are just two of the many things that are made possible through the insights of calculus. Our modern world would not be possible without managing the power of infinity.

Sunday, March 01, 2020

How Not to Be Wrong: The Power of Mathematical Thinking

How Not To Be Wrong is part an exploration of the joys of math, and part a manual on how to avoid getting duped (or duping oneself) with math. There is also a bit of namedropping of famous mathematicians for good measure. Politicians are great at coming up with good sounding, but meaningless numbers. Wisconsin may have claimed that its 5000 net new jobs accounted for 50% of all new jobs for a year. That could be technically correct. However, since some states lost jobs, a state with 12000 net new jobs would claim to account for 120% of net new jobs, showing the craziness of the data. Science is also rife with "statistically significant random results" from insufficiently large or small studies. There is also a "survivors bias", with many failed studies not being published. If 20 people study something, one is likely to randomly discover a significant result. If that person is the only one to publish, we don't realize the significant result was just random. The "5%" p-value acceptance threshold is just an arbitrary value. However, it does result in a serious amount of 'p-hacking' There are a lot more studies that just meet the threshold than would be suspected by a normal distribution. Similarly, people tend to favor numbers ending in 7 as "random numbers". Thus, an excessive preponderance of vote counts ending in 7, may indicate a rigged election.

Zero: The Biography of A Dangerous Idea

In Zero, Math journalist Charles Seife explores the concept of "0" and at the end brings in zero's cousin, infinity. Many ancient cultures did not have the concept of zero. The led to numerical systems like Roman numerals. It also resulted in odd year number. (1BC is followed immediately by 1 AD). Zero helped unlock new abilities in math, and made writing numbers easier. The author also explores Pythagoreans and their problems with irrational numbers (such as the square root of 2 that pops up in the pythagorean therom.) He mentions incidents where division by zero caused great calamities. Zero also opened the door the calculus and the concept of limits that approach zero (or infinity) Towards the end, the author spends a lot of time delving into worm holes and theoretical physics.

Wednesday, April 11, 2018

Fooled By Randomness

Fooled By Randomness explores the importance of random events in life and society. On the outset, the author states that he wanted this book to be fun to write, and tried to avoid too many citations. He does cite some literature, but more often he helps provide alternate explanations for results. For example, many studies have tried to tease out what makes successful businessmen. Intelligence is not seen as super important. However, the propensity to take risks does stand out. However, if you looked at bankrupt businessmen, you may see similar results, likely with an even higher "risk taker" rating. The highly successful may appear to be average because they are. They just happened to get lucky. The finance world tends to revere the young, successful traders. However, finding the next "big shot" is essentially a crap-shoot. One person may take risks and get lucky. However, many others will not have the same luck. An older trader is probably your best bet, because they have managed to survive for a long time without imploding.
It is very hard for us to separate out the "random luck" from "skill". Today CEOs get paid enormous salaries to lead companies. However, do they really bring anything to the table? It is difficult to precisely quantify the value that they add. It could be that they just happen to be charismatic and happened to be heading a well-run company. Lower level individual contributors tend to produce results that are much more easily quantified. But as you move up the management chain, randomness plays a larger and larger roll. Even companies as a whole benefit enormously from randomness. Microsoft became a mega software company because IBM used DOS and IBM's architecture became the dominant in the industry. A lot of dice rolls went their way and resulted in a mega company. How much of Bill Gates' fortune is due to luck and how much due to skill? His net worth may be a million times that of some contemporary programmers with equivalent talents. (This also brings in to place network and building effects. Due to "randomness", early success may lead to greater future opportunities that can help develop different skills in the future.)
Even when we know the role of randomness, we are still likely to "fall for it." This can sometimes result in self-defeating behavior, as the mental benefit from a gain less than the harm from a similar loss. It takes skill to avoid "distractions" of randomness and live our lives in the best way possible.

Wednesday, August 02, 2017

The Theory That Would Not Die: How Bayes' Rule Cracked the Enigma Code, Hunted Down Russian Submarines, and Emerged Triumphant from Two Centuries of Controversy

Bayes' rule seems very simple. However, it has produced a great deal of controversy throughout its history. Even the name itself is controversial. Bayes does appear to have been one of the first people to produce a paper on it. However, the paper we have was substantially edited by Richard Price and presented at the Royal Society after Bayes' death. Laplace later independently discovered the algorithm and ran with it. Since he was the more renowned mathematical mind, it would make sense to name it after him. However, it was later referred to as Bayes rule by those who popularized it, and that is what we have today.
The Theory That Would Not Die does not spend much time covering the details of Bayes' rule. It is assumed the reader already understands it, or will be able to understand it well enough by following the story line. Instead, the focus is on the conflicts between the "bayeseians" and the "frequentists". Bayes can help determine probabilities given scant data or unknown occurrences and was derided as "subjective". Frequency analysis deals with known observations as was considered a more theoretically accurate. Bayesian analysis would come and go in spurts during its history. In world war ii, it helped lead to cracking the German code and significantly helping the Allied war efforts. Alas, it was deemed so important that it was classified, and thus not disclosed to the general public. The ability to adjust probabilities based on past outcomes made it especially useful for insurance actuaries. Today it has applications in multitudes of fields from medical research to spam filters. It is great at helping to tease out the signal from the noise and find high probability answers given scant data.