Trying to extend distributive property of modulo operation to real numbers












0












$begingroup$


Here Wikipedia states that modulo operation is distributive:
$$a cdot b mod n = (a mod n)cdot (b mod n) mod n$$
Which is true for every natural number. Unfortunately it is not for rational ones:
given$q in Bbb Q, n in Bbb Z, qcdot n notin Bbb Z $.
$$qcdot n mod 1 ne 0 $$
$$ left{ begin{array}{c}q mod 1ne0\n mod 1 = 0 end{array}right.$$
Therefore $$(q mod 1)cdot(n mod 1)=0 $$
I was wondering if you guys have any idea on how to extend this very property to real numbers (or rational ones).










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$endgroup$












  • $begingroup$
    you can't, not if you mean real distributivity. The reason for that is that the modulo construction on integers is actually taking the quotient by "nice" subgroups which are closed under arbitrary multiplication (ideals). sadly however $mathbb{Q}$ is a field, and hence has no nontrivial prime ideals. (this corresponds precisely to your problem above, that as soon as you have a number vanishing in modulo, $1$ has to vanish as well)
    $endgroup$
    – Enkidu
    Dec 18 '18 at 14:28
















0












$begingroup$


Here Wikipedia states that modulo operation is distributive:
$$a cdot b mod n = (a mod n)cdot (b mod n) mod n$$
Which is true for every natural number. Unfortunately it is not for rational ones:
given$q in Bbb Q, n in Bbb Z, qcdot n notin Bbb Z $.
$$qcdot n mod 1 ne 0 $$
$$ left{ begin{array}{c}q mod 1ne0\n mod 1 = 0 end{array}right.$$
Therefore $$(q mod 1)cdot(n mod 1)=0 $$
I was wondering if you guys have any idea on how to extend this very property to real numbers (or rational ones).










share|cite|improve this question









$endgroup$












  • $begingroup$
    you can't, not if you mean real distributivity. The reason for that is that the modulo construction on integers is actually taking the quotient by "nice" subgroups which are closed under arbitrary multiplication (ideals). sadly however $mathbb{Q}$ is a field, and hence has no nontrivial prime ideals. (this corresponds precisely to your problem above, that as soon as you have a number vanishing in modulo, $1$ has to vanish as well)
    $endgroup$
    – Enkidu
    Dec 18 '18 at 14:28














0












0








0





$begingroup$


Here Wikipedia states that modulo operation is distributive:
$$a cdot b mod n = (a mod n)cdot (b mod n) mod n$$
Which is true for every natural number. Unfortunately it is not for rational ones:
given$q in Bbb Q, n in Bbb Z, qcdot n notin Bbb Z $.
$$qcdot n mod 1 ne 0 $$
$$ left{ begin{array}{c}q mod 1ne0\n mod 1 = 0 end{array}right.$$
Therefore $$(q mod 1)cdot(n mod 1)=0 $$
I was wondering if you guys have any idea on how to extend this very property to real numbers (or rational ones).










share|cite|improve this question









$endgroup$




Here Wikipedia states that modulo operation is distributive:
$$a cdot b mod n = (a mod n)cdot (b mod n) mod n$$
Which is true for every natural number. Unfortunately it is not for rational ones:
given$q in Bbb Q, n in Bbb Z, qcdot n notin Bbb Z $.
$$qcdot n mod 1 ne 0 $$
$$ left{ begin{array}{c}q mod 1ne0\n mod 1 = 0 end{array}right.$$
Therefore $$(q mod 1)cdot(n mod 1)=0 $$
I was wondering if you guys have any idea on how to extend this very property to real numbers (or rational ones).







modular-arithmetic real-numbers irrational-numbers integers






share|cite|improve this question













share|cite|improve this question











share|cite|improve this question




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asked Dec 18 '18 at 12:19









Lyn CassidyLyn Cassidy

436




436












  • $begingroup$
    you can't, not if you mean real distributivity. The reason for that is that the modulo construction on integers is actually taking the quotient by "nice" subgroups which are closed under arbitrary multiplication (ideals). sadly however $mathbb{Q}$ is a field, and hence has no nontrivial prime ideals. (this corresponds precisely to your problem above, that as soon as you have a number vanishing in modulo, $1$ has to vanish as well)
    $endgroup$
    – Enkidu
    Dec 18 '18 at 14:28


















  • $begingroup$
    you can't, not if you mean real distributivity. The reason for that is that the modulo construction on integers is actually taking the quotient by "nice" subgroups which are closed under arbitrary multiplication (ideals). sadly however $mathbb{Q}$ is a field, and hence has no nontrivial prime ideals. (this corresponds precisely to your problem above, that as soon as you have a number vanishing in modulo, $1$ has to vanish as well)
    $endgroup$
    – Enkidu
    Dec 18 '18 at 14:28
















$begingroup$
you can't, not if you mean real distributivity. The reason for that is that the modulo construction on integers is actually taking the quotient by "nice" subgroups which are closed under arbitrary multiplication (ideals). sadly however $mathbb{Q}$ is a field, and hence has no nontrivial prime ideals. (this corresponds precisely to your problem above, that as soon as you have a number vanishing in modulo, $1$ has to vanish as well)
$endgroup$
– Enkidu
Dec 18 '18 at 14:28




$begingroup$
you can't, not if you mean real distributivity. The reason for that is that the modulo construction on integers is actually taking the quotient by "nice" subgroups which are closed under arbitrary multiplication (ideals). sadly however $mathbb{Q}$ is a field, and hence has no nontrivial prime ideals. (this corresponds precisely to your problem above, that as soon as you have a number vanishing in modulo, $1$ has to vanish as well)
$endgroup$
– Enkidu
Dec 18 '18 at 14:28










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