Zerosumfree monoid

In abstract algebra, an additive monoid (M, 0, +) is said to be zerosumfree, conical, centerless or positive if nonzero elements do not sum to zero. Formally:

(\forall a,b\in M)\ a + b = 0 \implies a = b = 0 \!

This means that the only way zero can be expressed as a sum is as 0 + 0.

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