Mathematician's letters

• Proof ending
• Logician's "as was proven"
• Geometer's sign-off
• Logician's abbr.
• "That's how it's done"
• End of a demonstration?
• Math abbr.
• "And that's how it's done!", for short

Wikipedia Word definitions in Wikipedia
QED is a line-oriented computer text editor that was developed by Butler Lampson and L. Peter Deutsch for the Berkeley Timesharing System running on the SDS 940 . It was implemented by L. Peter Deutsch and Dana Angluin between 1965 and 1966. QED (for "quick ...

Wiktionary Word definitions in Wiktionary
alt. quod erat demonstrandum (Latin ''what had to be proved'' or ''what was to be demonstrated''). interj. quod erat demonstrandum (Latin ''what had to be proved'' or ''what was to be demonstrated''). n. quantum electrodynamics.