# Definition:Atom (Logic)

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*This page is about Atom in the context of Logic. For other uses, see Atom.*

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## Definition

In a particular branch of logic, certain concepts are at such a basic level of simplicity they can not be broken down into anything simpler.

Those concepts are called **atoms** or described as **atomic**.

Different branches of logic admit different **atoms**.

### Propositional Logic

In propositional logic, the **atoms** are statements.

## Also defined as

Some sources define **atom** to mean what is defined in $\mathsf{Pr} \infty \mathsf{fWiki}$ as a literal: a statement variable or the negation of a statement variable.

## Also known as

Some sources use the longer form **atomic sentence**.

## Linguistic Note

The word **atom** comes from the Greek **ἄτομον**, meaning **unbreakable** or **indecomposable**.

It is pronounced with a short **a**, as ** at-tom**, as opposed to

**.**

*ay*-tom

## Sources

- 1998: David Nelson:
*The Penguin Dictionary of Mathematics*(2nd ed.) ... (previous) ... (next):**atomic sentence** - 2000: Michael R.A. Huth and Mark D. Ryan:
*Logic in Computer Science: Modelling and reasoning about systems*... (previous) ... (next): $\S 1.1$: Declarative sentences - 2008: David Nelson:
*The Penguin Dictionary of Mathematics*(4th ed.) ... (previous) ... (next):**atomic sentence**