If and Only If \iff

When to use If and Only If

Logical equivalence In source, start from the exact \iff command instead of imitating the rendered glyph with Unicode characters or manual spacing. This keeps the expression editable and gives the renderer enough structure to apply mathematical spacing correctly.

Syntax

\iff

The documented syntax belongs to amsmath. Keep every required argument, brace pair, and environment boundary intact when moving the command between an editor, Markdown processor, notebook, or publishing system.

Example

P\iff Q

Rendered output

P ⇔ Q

Copy and compatibility checks

• Copy \iff exactly; changing its case or removing a leading backslash can turn it into plain text.
• Confirm that the destination loads amsmath before relying on this command.
• Render the example once, then inspect grouping, limits, scripts, and spacing before publishing.