The 'greater than' symbol in math is >, which means the number on the left is bigger than the one on the right. For example, 5 > 3 is read as '5 is greater than 3'.

René Descartes (also often translated as Descartes) was a French philosopher, mathematician, and physicist born on March 31, 1596, and passed away on February 11, 1650. He's commonly called the 'father of modern science.' His most famous quote is 'I think, therefore I am,' and he also invented the Cartesian coordinate system that we often use in math class.

"Greater than or equal to" is a mathematical operator, commonly used to compare two numbers. It's a combination of the 'greater than' symbol (>) and the 'equal to' symbol (=), meaning the number on the left is greater than or equal to the number on the right.

The 'Cartesian network' in math usually refers to an interconnection network built through the Cartesian product of graphs, not the Cartesian coordinate system itself; the latter is often mistakenly called a 'Cartesian network,' but it's actually a 'Cartesian coordinate grid'.

Substitution usually refers to the method of elimination in math, mainly used to solve systems of two linear equations, and the core idea is to turn a "two-variable" problem into a "one-variable" one to solve it.

Algebra is a fundamental branch of math that mainly studies using symbols (like letters) to represent numbers for operations, reasoning, and analyzing numerical relationships. In English, it's called Algebra. It's more than just arithmetic; it's about finding general ways to solve problems through abstract symbols.

David Hilbert (January 23, 1862 – February 14, 1943), born in Königsberg, East Prussia, was a mathematician

"Unit conversion ratio" is not a standard math term. It usually refers to the ratio between two values with the same dimension in a unit conversion (i.e., the conversion factor). Essentially, it's the proportional relationship of the same physical quantity in different units.

The identity element is a basic concept in algebraic structures in mathematics. It refers to a special element that doesn’t change the value of other elements under a specific operation. It’s like the “invisible person” in an operation – when combined with any element, the other element stays the same, like 0 in addition and 1 in multiplication.

Navigation is the technology or process of guiding people or devices from the starting point to the destination safely and accurately. It mainly deals with the three core questions: 'Where am I, where am I going, and how do I get there?'