How would one say "Suppose that A?" I am looking for the way that this might be translated for mathematics.

  • More context would certainly be helpful.
    – Walter
    Jul 1, 2017 at 8:47
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2 Answers 2


There is no literal translation for "Suppose that A" as a complete sentence that sound natural to me. The best I can do is "Man nehme an, dass A" or "Nehmen wir an, dass A". The first sounds somewhat stilted, the second depends on you being fine using "we" in your text (literally it's "Let's suppose that A", which some people are fine using and some aren't.)

You can alse use "angenommen, dass A" or "unter der Annahme, dass A", which both translate to "supposing that A". (If A is a formula, you could only use "angenommen": "angenommen P = NP".) Another thing that might be good situationally is "Sei A X", which translates to "Let A be X". It sounds weird to my non-mathematician ears, but I believe people still use it.

  • Is using "angenommen" as good/common as any of these options?
    – user109871
    Jun 30, 2017 at 1:20
  • 1
    I'm assuming here that you don't literally write "Suppose that A", but that A stands for some longer proposition. In that case, I think it depends on whether a sentence or a formula follows. For a sentence, I would always use "angenommen dass A". For a formula, you could just use "angenommen": "angenommen P = NP" sounds perfectly fine. I'll edit the post accordingly.
    – sgf
    Jun 30, 2017 at 1:37
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    Phrases using Sei ... actually are standard for mathematicians. Examples: Sei ω eine geschlossene Differentialform ... ; sei N ein Normalteiler .... Jun 30, 2017 at 7:05
  • @MartinPeters Thanks, I was unsure about that.
    – sgf
    Jun 30, 2017 at 10:49


You could add more context around your phrase, then it would be more clear what your query refers to exactly, but I suppose you refer to an assumption that is invalidated as part of the proof.

Then you should use:

Angenommen, X erfüllt Y; dann wäre .....
Suppose that X satisfies Y; then ..... would be .....

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