Reading as a god

Chapter 168 Strange Library!
After Zhang Shan clarified his work tasks, he decisively activated 580 Quiet Reading Cards and 200 Premium Reading Cards.

（此后剩余静享读书卡×500张、妙享读书卡×20张、“卓越级英语口语技能10分钟体验卡”×9张、“卓越级编程技能10分钟体验卡”×29张）
After using these two cards at the same time, Zhang Shan noticed that there was an extra score of inspiration and activity in the meson space.

With the change of Zhang Shan's behavior, this value has been fluctuating~
Zhang Shan chose to read a large number of basic mathematics books and some current research results on the four-color problem during the effective stage of enjoying the reading card.

Zhang Shan regretted choosing to study topics related to the four-color problem.

What a hassle~
The trouble starts with the fact that too many other branches of mathematics are involved.

Although the four-color problem appears to be a discrete mathematics problem.

But Zhang Shan still needs to do a lot of homework on other branches of mathematics~
For more than a century, mathematicians have racked their brains to prove the four-color theorem, and the concepts and methods introduced have stimulated the growth and development of topology and graph theory.

Conversely, if Zhang Shan wants to study the four-color theorem, it is necessary to work hard on topology and graph theory.

Topology is a subject that studies the properties of geometric figures or spaces that remain unchanged after continuously changing their shapes.It only considers the positional relationship between objects without considering their shape and size.In topology, important topological properties include connectivity and compactness.

Graph Theory is a branch of mathematics.It takes pictures as its research object.A graph in graph theory is a graph composed of a number of given points and a line connecting two points. This graph is usually used to describe a certain relationship between certain things. Points represent things, and points connect two points. The line of represents that there is such a relationship between the corresponding two things.

However, the branches involved are far more than that. The so-called mobilization of the whole body is just like this.

Zhang Shan's main effort is still spent on discrete mathematics.

Discrete mathematics is a mathematical discipline that studies the structure of discrete quantities and their interrelationships, and is an important branch of modern mathematics.The meaning of discrete refers to different connected elements, mainly to study the structure and mutual relationship based on discrete quantities, and its objects are generally limited or countable elements.Discrete mathematics is widely used in various disciplines, especially in the field of computer science and technology. At the same time, discrete mathematics is also a professional course for computer majors, such as programming language, data structure, operating system, compilation technology, artificial intelligence, database, algorithm design and analysis, theoretical computer science foundations and other essential prerequisite courses.Through the study of discrete mathematics, not only can you master the description tools and methods for dealing with discrete structures, and create conditions for the study of subsequent courses, but also improve your ability of abstract thinking and strict logical reasoning, and lay a solid foundation for future participation in innovative research and development. Foundation.

These reasons are secondary, and the real key factor is that the four-color problem itself is an important topic of discrete mathematics.It can even be said that the research on the four-color problem established the position of discrete mathematics in modern mathematics.

But the real reason goes much deeper than that:

With the advent of the information age, the mainstream position of continuous mathematics represented by calculus in the era of industrial revolution has changed, and the importance of discrete mathematics has gradually been recognized by people.The ideas and methods taught by discrete mathematics courses are widely reflected in various fields of computer science and technology and related majors, from scientific computing to information processing, from theoretical computer science to computer application technology, from computer software to computer hardware, from artificial intelligence From cognitive systems to cognitive systems, all are closely related to discrete mathematics.Since the digital electronic computer is a discrete structure, it can only deal with discrete or discretized quantitative relationships. Therefore, both computer science itself and modern scientific research fields closely related to computer science and its applications are faced with how to deal with Discrete structure establishes the corresponding mathematical model; how to discretize the mathematical model established with the continuous quantity relationship, so that it can be processed by the computer.

Discrete mathematics is traditional logic, set theory (including functions), number theory basis, algorithm design, combinatorial analysis, discrete probability, relation theory, graph theory and trees, abstract algebra (including algebraic systems, groups, rings, domains, etc.), A comprehensive subject that brings together Boolean algebra, computational models (language and automata), etc.The application of discrete mathematics pervades many fields of modern science and technology.

Discrete mathematics can also be said to be the basic core subject of computer science...

Speaking of discrete mathematics, it covers the following:
1.Set theory part: sets and their operations, binary relations and functions, natural numbers and sets of natural numbers, cardinality of sets.

2.Graph theory: basic concepts of graphs, Euler graphs and Hamiltonian graphs, trees, matrix representation of graphs, planar graphs, graph coloring, dominating sets, covering sets, independent sets and matching, weighted graphs and their applications.

3.Algebraic structure: basic concepts of algebraic systems, semigroups and singular points, groups, rings and fields, lattices and Boolean algebras.

4.Part of combinatorics: combinatorial existence theorem, basic counting formula, combinatorial counting method, combinatorial counting theorem.

5.Mathematical logic part: propositional logic, first-order predicate calculus, principle of resolution.

Although it seems quite complicated, Zhang Shan only focuses on the knowledge involved in the four-color problem based on the principle of discussing the matter.

Still, it's quite a lot of work.

But let’s take it slowly, 580 Jingxiang reading cards correspond to 580 hours.

Calculated according to the hard-working scientific research dogs who work 14 hours a day, this is equivalent to more than 40 days for them.

As long as you follow the steps step by step, it's fine to be so self-willed as a hanger!
~~~~~~
After reading a lot of basic mathematics books, Zhang Shan next looked at the various efforts made by people in history to prove the four-color problem.

The four color theorem of maps was first proposed by a British college student named Francis Guthrie.

The content of the four-color problem is "Any map that uses only four colors can make countries with a common border different colors." Just tag it.

In mathematical language, it means "arbitrarily subdividing the plane into non-overlapping areas, and each area can always be marked with one of the four numbers 1234 without causing two adjacent areas to get the same number." The adjacent area referred to here means that an entire section of the boundary is common.Two regions are not adjacent if they meet at only one point or a finite number of points.Because coloring them with the same color won't cause confusion.

He first chose to read content related to the five-color theorem.

The five-color theorem is a weak proposition of the four-color theorem.

Easier to prove than the four-color theorem. In 1879, Alfred Bray Kemp gave a proof of the four-color theorem, which was accepted at the time, but 11 years later, Percy John Sheawood found an error in Kemp's proof, He modified Kemp's proof and obtained the five-color theorem.

The five-color theorem is a conclusion in graph theory: divide a plane into several areas, color these areas, and ensure that any adjacent areas do not have the same color, then the required colors do not exceed five.

After that, Zhang Shan began to study the proof of the four-color problem at the University of Illinois in the United States~
Speaking of which, this is the first proof of the four-color problem.

In June 1976, on two different electronic computers at the University of Illinois in the United States, it took 6 hours and made 1200 billion judgments. As a result, none of the maps required five colors, and finally proved the four-color theorem , a sensation in the world.

The key to the proof of the four-color theorem can be summarized as the intersection of two straight lines in a two-dimensional plane.

1. Represent different areas on the map with different points.

2. The connection between points is used to represent the adjacent logical relationship between two areas on the map, so lines cannot intersect (that is, there cannot be intersections without public intersections), otherwise it will exceed A two-dimensional plane is created, and this plane is temporarily called a logical plane, which only reflects the relationship between regions, and does not reflect the actual location.

Zhang Shan now has good language literacy and a lot of programming language foundation.

But in front of mathematics, I am still a child picking up shells at the beach~
Although a little immature, Zhang Shan also discovered the fun of doing this!
In the process of Zhang Shan constantly picking up "shells".

Time is like sand, slipping away from your fingertips quietly~
Although it is only the time in the meson space, Zhang Shan still races against time~
After reading books for about 90 hours with Jingxiang reading card in the meson space, Zhang Shan saw that the inspiration and activity finally reached [-] points~
Finally, all the Jingxiang reading cards have been consumed, and the Youxiang reading card has taken effect~
Zhang Shan only felt that the mental projection of his original image into the meson space came to a strange place with a burst of space-time distortion. According to the system prompt, this is the so-called meson space library.

Zhang Shan soon realized that this was not the first time he encountered a similar situation.

His thoughts suddenly returned to some encounters when he entered the office (see Chapter 57):

"Speaking of which, this is Zhang Shan's first visit to this Zen master-style super-large study room (hereinafter referred to as the large Zen room for convenience), and according to the information in his mind, Zhang Shan knows that this large Zen room has an area of ​​660 square meters.

Originally, Zhang Shan thought it was an empty space similar to a matchbox, but after entering it, he found something strange. The 666-square-meter space is obviously divided into several different areas in terms of style:
One of the areas is about [-] square meters. Judging from the decoration style, it is quite similar to the style of Taoism in my country. A strong and powerful "Tao" character is hung on the deepest wall of this area, a large eight-diagram map, and various Some clothing such as Taoist robes;
The other area is about [-] square meters. Zhang Shan regarded it as a dojo for Fusang at a glance. The entire area also deliberately made the interior into a Japanese style, and there are many kimonos and other clothing.

Although a little inexplicable, these two are relatively within the category that Zhang Shan can understand.

In the other area, Zhang Shan is completely clueless. There are only two colors of black and white in the entire space. The large area of ​​irregular black and white only makes Zhang Shan feel extremely abrupt.Zhang Shan even feels that the space inside is distorted when the line of sight is deviated.

In this environment, not to mention practicing Zen, even sitting in meditation inside Zhang Shan will feel depressing.However, this area is still the largest, Zhang Shan estimated that it would be at least [-] square meters. "

At that time, Zhang Shan was quite baffled when he faced the [-]-square-meter Zen room with only black and white colors!
God knows that the interior decoration of the so-called Meson Space Library is in this style!
Zhang Shan's whole body is in bad shape!If he knew that he would encounter this kind of situation before, Zhang Shan would rather spend some time every day in the black and white style meditation room to exercise his ability to bear this kind of environment.

Looking at it now, what a bitter word~
Don't say that you are reading some advanced books here, just staying here is a kind of torment~
And it is different from the constant source of energy that can be felt when the Jingxiang Reading Card is in effect:
In the meson space library, Zhang Shan seems to have lost the energy source buff in an instant.

It can only be undertaken by relying solely on its own mental strength and willpower!
But Zhang Shan chose the 200-hour preferential reading card because he was still a newborn calf.

Zhang Shan originally thought that the books in the Jiezi Space Library were wordless books, and they would automatically come to his mind just by looking at them.

Now it seems that this is obviously not the case, although a large amount of knowledge that is not available in the world has been listed~
But obviously it needs Zhang Shan to digest and absorb through his own understanding.

He probably understands the purpose of the system~
Heaven will send a great mission to human beings, they must first suffer their minds and wills, exhaust their muscles and bones, starve their bodies and skins, empty their bodies, and disturb their actions.

In addition, the writing is originally for the top journal, if it is done overnight, it seems too boring.

Speaking of top issues:

Domestic top journals are the core journals we are familiar with. Domestic core journals are the top journals of domestic academic journals. There are seven categories of core journals, each of which is strictly selected according to certain standards. It can be said that they are top-notch in each major The role of core journals is very obvious in the domestic academic circles, and the recognition of professional title promotion, graduation, award awards and other fields is very high, especially the core journals of NTU and Peking University, which are of particularly high value.

The top foreign journals are sci journals. The publication of sci journals is the touchstone of international academic level. Once sci journal papers can be published, it means that the author's scientific research ability has reached the international advanced level. Many domestic scientific research institutions and colleges and universities attach great importance to sci journals The publication of the thesis is also the most powerful weight for personal promotion and graduation.

Whether it is a domestic top journal or an international top journal, it is very difficult to publish, and the publication of an international top journal is even more difficult, because English writing is required, so the value of a top journal is high, but it takes a lot of effort to publish .

(End of this chapter)