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rational number

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Mathematics Subject Classification

13B30 no label found11A99 no label found03E99 no label found


Back in my day, we called the rational numebers {p/q : p, q are integers}


hopefully q was a non-zero integer in your day :)

It took you five years to prepare that response?



In general it has been more usefull, more extensible, to define ”rational numbersPlanetmathPlanetmathPlanetmath” as a pair (a,b) with a multiplicationPlanetmathPlanetmath and addition rule. And then take Integers as an example.

Addition rule (a,b)+(c,d) (a*d+b*c,b*d)

Multiplication rule: (a,b)*(c,d) (a*c,b*d)

a,b,c,d ∈Z and b,d != 0

Definitions like this allow one to manipulate items from a more general ring and also use the usuall nomeclature a/b=c/d . This includes certain exotic cases in Algebraic GeometryPlanetmathPlanetmath.

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