Articles on logic, mathematics, and computer science.

## Why Did Sumerians Use the Sexagesimal System?

Sumerians used sexagesimal numerals not only because the number 60 has many divisors or it is countable on the fingers of both hands but because 60 is the least common multiple of the number of fingers of both hands and the number of months in a year. The Chinese cycle of the Stems and Branches has the same structure as the Sumerian sexagesimal system and we can assume the Chinese sexagesimal cycle was imported from Mesopotamia to China. Today both the Mesopotamian sexagesimal system and the Chinese sexagenary cycle are apt to be explained in terms of the 60-year conjunction cycle of Jupiter and Saturn, such an interpretation of posterity should not conceal the original implication.

## What Is an Indefinite Integral?

An indefinite integral is the integral whose lower boundary is constant and whose upper boundary is variable and it should be distinguished from a primitive integral that just restores primitive functions. Constants of primitive integration should also be distinguished from constants of indefinite integration that the lower boundary produces. Integration is often said to be the inverse operation of differentiation, but it is mathematically false. Since a set of primitive functions and a set of integrands is not in one-to-one but in many-to-one relationship, integration cannot be an inverse mapping. Differentiation and integration are in the relationship of analysis and synthesis. As a derivative has only partial information on the original function, it cannot restore the whole information. Contents 1. The previous explanation of the indefinite integral 2. The indefinite integral should be distinguished from the primitive 3. Integration produces two kinds of constants 4. Integration is ...

## The Copernican Revolution of Infiniteness

When infinitesimal calculus was first established, the limit of a function was defined in terms of infinitesimal or infinity. As the naïve way at that time contradicted itself, new methods such as the epsilon-delta definition and non-standard analysis were devised to avoid the contradiction. Although mathematicians are not aware of it, it is Kant’s transcendental idealism that lays the foundation for these methods. That is to say, these methods succeed in solving the paradox of infiniteness because they abandon the cognition of “infiniteness in itself” and accomplish the Copernican Revolution that converts the cognition of infiniteness into the infiniteness of cognition.

## Why Are Cartesian Coordinate Systems Cartesian?

A Cartesian coordinate system is named after René Descartes. But Descartes did not first invent the Cartesian coordinate system nor did he first establish analytic geometry on the ground of the Cartesian coordinate system. Still it deserves its name, because the method of the Cartesian coordinate system is similar to that of Cartesian philosophy.