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What is the difference between proof and prove in math?

Published in Mathematical Logic 4 mins read

The difference between 'proof' and 'prove' in mathematics lies in their grammatical function and the specific role they play in establishing mathematical truth: 'proof' is a noun referring to the evidence or argument, while 'prove' is a verb describing the act of validating that evidence.

Understanding 'Proof' in Mathematics

In mathematics, a proof is a rigorous, logical argument that establishes the truth of a statement, proposition, or theorem. It is the finished product—the "evidence" that justifies a mathematical claim. Think of it as the complete justification or demonstration for why a statement is true.

What is a Mathematical Proof?

A mathematical proof is a sequence of logical steps, starting from axioms (self-evident truths) or previously established theorems, and leading to the conclusion that a new statement is undeniably true. It is generally a body of evidence used to justify an argument. Without a valid proof, a mathematical statement remains a conjecture, regardless of how many examples might suggest its truth.

Key characteristics of a mathematical proof:

  • Logical Rigor: Every step must logically follow from the previous ones.
  • Deductive Reasoning: It typically uses deductive reasoning, moving from general principles to specific conclusions.
  • Irrefutable: Once proven, a statement is considered a mathematical truth.
  • Formal Structure: Often follows a structured format, using definitions, axioms, postulates, and established theorems.

Example of a Proof:
The proof that the sum of two even numbers is always an even number involves showing:
Let $m$ and $n$ be any two even numbers.
By definition, an even number can be written as $2k$ for some integer $k$.
So, $m = 2a$ and $n = 2b$ for some integers $a$ and $b$.
Their sum is $m + n = 2a + 2b$.
Factoring out 2, we get $2(a + b)$.
Since $a$ and $b$ are integers, their sum $(a + b)$ is also an integer.
Let $c = a + b$. Then $m + n = 2c$.
Since $m + n$ can be expressed as $2$ times an integer, $m + n$ is an even number. This entire sequence of steps is the proof.

Understanding 'Prove' in Mathematics

To prove a statement in mathematics means to carry out the act of demonstrating its truth through a rigorous logical argument. It is the verb form, the process of validating the presence of something by evidence. When a mathematician sets out to prove a theorem, they are undertaking the task of constructing the logical argument that will establish its validity.

The Act of Proving

Proving involves the intellectual effort of constructing the sequence of logical steps, selecting appropriate axioms and definitions, and applying deductive reasoning to reach the desired conclusion. It's the journey of discovery and justification.

The process of proving often involves:

  • Understanding the statement: Clearly defining what needs to be shown.
  • Recalling relevant definitions and theorems: Accessing the foundational knowledge.
  • Choosing a proof technique: Deciding whether to use direct proof, proof by contradiction, induction, etc.
  • Constructing the argument: Writing down the logical steps.
  • Reviewing and refining: Ensuring clarity, correctness, and completeness.

Example of Proving:
A student is asked to prove that the square root of 2 is an irrational number. The act of sitting down, considering the definitions of rational and irrational numbers, choosing a proof by contradiction, writing out the steps, and checking the logic – all of this constitutes the process of proving. Once they have successfully constructed the argument, they will have produced a proof.

Key Differences Summarized

Feature Proof Prove
Part of Speech Noun Verb
Meaning The evidence, argument, or logical demonstration itself The act of demonstrating or establishing truth
Role The established justification for a statement The process of creating that justification
Question "What is the proof?" "How do you prove it?"
Outcome A completed, validated argument or document The successful completion of a logical demonstration

Why This Distinction Matters in Math

Understanding the distinction between 'proof' and 'prove' is fundamental in mathematics because it highlights both the product and the process that are central to the discipline. Mathematics isn't just about stating facts; it's about rigorously establishing them.

  • Rigorous Foundation: Every mathematical proof adds to the body of established knowledge, forming the bedrock upon which further discoveries are built.
  • Critical Thinking Skill: The ability to prove a statement develops critical thinking, logical reasoning, and problem-solving skills, which are invaluable not just in mathematics but in many other fields.
  • Communication: Presenting a clear and concise proof is a crucial aspect of mathematical communication, ensuring that others can understand and verify the validity of new findings.

In essence, you prove something by constructing a proof. The former is the action, the latter is the result.