# Does a theorem have to be proven?

### Table of Contents

- Does a theorem have to be proven?
- Do postulates require proof?
- Does a corollary need a proof?
- Can a corollary be proved by a theorem?
- Can theorems be proven wrong?
- Can you disprove a theorem?
- What is the difference between a theorem a postulate and a proof?
- Are theorems proven true with postulates?
- What is a corollary principle?
- Can a corollary be used as a grader?
- Which is the best description of a corollary?
- When does an author use a corollary in a theorem?
- Which is more important a lemma or a corollary?

### Does a theorem have to be proven?

A theorem is a statement that **has been proven to be true based on axioms and other theorems**. A proposition is a theorem of lesser importance, or one that is considered so elementary or immediately obvious, that it may be stated without proof.

### Do postulates require proof?

A postulate is a **statement that is assumed true without proof**. A theorem is a true statement that can be proven.

### Does a corollary need a proof?

Corollary — **a result in which the (usually short) proof relies heavily on a given theorem** (we often say that “this is a corollary of Theorem A”). Proposition — a proved and often interesting result, but generally less important than a theorem. ... Axiom/Postulate — a statement that is assumed to be true without proof.

### Can a corollary be proved by a theorem?

A corollary is a statement that can be **easily proved** using a theorem.

### Can theorems be proven wrong?

**We cannot be 100% sure that a mathematical theorem holds**; we just have good reasons to believe it. As any other science, mathematics is based on belief that its results are correct. Only the reasons for this belief are much more convincing than in other sciences.

### Can you disprove a theorem?

Yes you are correct. **One counterexample is enough to disprove a theorem**. You can check whether it is a counterexample by taking all conditions for the theorem and then negating the proposition.

### What is the difference between a theorem a postulate and a proof?

The main difference between postulates and theorems is that **postulates are assumed to be true without any proof while theorems can be and must be proven to be true**.

### Are theorems proven true with postulates?

The difference between postulates and theorems is that **postulates are assumed to be true**, but theorems must be proven to be true based on postulates and/or already-proven theorems. ... The two isosceles-triangle theorems — If sides, then angles and If angles, then sides — are an example.)

### What is a corollary principle?

Corollary principle: **Where harm cannot be avoided, we are obligated to minimize the harm we do**. ... Corollary principle: It is wrong to waste resources that could be used for good. Combining beneficence and nonaleficence: Each action must produce more good than harm.

### Can a corollary be used as a grader?

- A corollary is just another word for a theorem. However, it is a theorem that mainly uses the results of the another, more general (some would argue more important) theorem. Thus, as a grader if you are proving a corollary.

### Which is the best description of a corollary?

- A Corollary could be described as a "post-
**proof**." A corollary is something that follows almost obviously from a theorem you've proved. You work to prove something, and when you're all done, you realize, "Oh my goodness! If this is true, than [another proposition] must also be true!"

### When does an author use a corollary in a theorem?

- When an author uses a corollary, he is saying that this result can be discovered or deduced by the reader by himself, using as a tool some theorem or definition explained previously. Below are two theorems (which will not be proved), each followed by one or more
**corollaries**that are deduced from said theorem.

### Which is more important a lemma or a corollary?

- Lemma — a minor result whose sole purpose is to help in proving a theorem. Corollary — a result in which the (usually short) proof relies heavily on a given theorem ( we often say that “this is a corollary of Theorem A”). Proposition — a proved and often interesting result, but generally less important than a theorem. Do axioms require proof?