An algebraic integer is a root of a monic (i.e. leading coefficient is 1) polynomial with integer coefficients. . . . . . .
Wikipedia: Algebraic integer
Mathworld: Algebraic Integer
Fact archive: Algebraic integer
Construction -- Construction of sets of numbers, starting with the original Peano Axioms, formulated so that zero is included in the set of natural numbers. (See Is Zero a Natural Number?)
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