Factorization of floor functions of fractions

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Discussion Overview

The discussion revolves around the factorization of floor functions of fractions, specifically focusing on the case where the numerator is a factorial and the denominator is composed of factors that divide the factorial but potentially to larger exponents. Participants explore whether it is possible to predict the factorization of the floor function based on the properties of the numerator and denominator.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions if there is a way to predict the factorization of the floor function of a fraction greater than 1, particularly when the numerator is a factorial.
  • Another participant requests clarification and examples to better understand the initial inquiry.
  • A participant proposes a specific case where B equals x! and A is x-smooth, exploring whether there exists an A such that floor(B/A) has no prime factors less than or equal to x.
  • Counterexamples are provided to challenge the idea that certain conditions can guarantee that floor(B/A) has no common factors with B, particularly highlighting cases where the gcd(B, floor(B/A)) does not equal 1.
  • Further exploration is made into whether there are parameters for A that would ensure that gcd(B, floor(B/A)) remains equal to 1 under specified conditions.

Areas of Agreement / Disagreement

Participants express disagreement regarding the conditions under which the floor function's factorization can be predicted. There is no consensus on whether specific parameters can guarantee that floor(B/A) has no common factors with B.

Contextual Notes

The discussion includes limitations related to the assumptions about the properties of A and B, as well as the implications of the gcd condition. The exploration of counterexamples indicates that the relationships may not hold universally.

DirichletHole
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hey so

if you are taking a floor function of a fraction >1, is there any way to predict anything about it's factorization?

what about when the numerator is a factorial and the denominator is made up of factors that divide said factorial but to larger exponents then those that divide the factorial?

any info welcome
 
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DirichletHole said:
if you are taking a floor function of a fraction >1, is there any way to predict anything about it's factorization?

It isn't clear what you are asking. I suggest you give some examples.
 
ok. hmm...

say you are looking at floor(B/A)

based on B and/or A, is there anyway to determine the factors of floor(B/A)?

specifically B will be equal to x! (x factorial for any x that is a pos int) with all common factors of A removed. A will be x-smooth, less than B, and based on the rules for B clearly coprime to B, but aside from that there are no rules set for A. Is there perhaps an A s.t. floor(B/A) will have no prime factors less than or equal to x?
 
Counterexample: Let x=4.
A=x+1=5
B=4!=24, no factors to remove.
Clearly coprime.

floor(B/A)=4, which has a factor smaller than x=4.
 
mfb said:
Counterexample: Let x=4.
A=x+1=5
B=4!=24, no factors to remove.
Clearly coprime.

floor(B/A)=4, which has a factor smaller than x=4.

first off, one of the requirements of A is that it only has prime factors less then or equal to x.
secondly, I already know that it is very possible for an example such as you have given to exist. What I want to know is:
Are there PARAMETERS that make it impossible for floor(B/A) to have common factors with B?

in other words
when x is any positive integer > 3
for A is divisible only by prime factors less then or equal to x
for B = x! with all the prime factors shared with A divided out so that gcd(B,A) = 1
are there any functions that satisfy the requirements of A such that the following statement always holds true:
gcd(B, floor(B/A)) = 1
?
 

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