1
$\begingroup$

Let $x_1,x_2,x_3$ be indeterminates. Fix an integer $k\geq 3$. Consider the set $M$ of all monomials of the form $x_1^{i_1}.x_2^{i_2}.x_3^{i_3}$ where each $i_j\in \mathbb{N}$ with $i_j\geq 1$ and $i_1+i_2+i_3 = k$.

Fix an arbitrary $F\in M$ and write $F = x_1^{a}.x_2^{b}.x_3^{c}$.

Does there exist a triple $(w_1, w_2, w_3)$, with each $w_i\in \mathbb{N}$ and $w_i\geq 1$, such that $$a.w_1 + b.w_2 + c.w_3 < i_1.w_1 + i_2.w_2 + i_3.w_3, \forall G = x_1^{i_1}.x_2^{i_2}.x_3^{i_3}\in M\backslash\{F\}?$$ In the exponential case, same question replaced by $a^{w_1}+ b^{w_2}+ c^{w_3}<i_1^{w_1}+i_2^{w_2}+ i_3^{w_3}$.

Positive example: $k = 4$ on three indeterminates. Then if $F$ corresponds to the element of $B_4$ with exponents $(2,1,1)$, then for any $w_2, w_3>1$, $w = (1,w_2,w_3)$ has the desired property.

Sometimes this question has a negative answer: e.g. k=4 on only two indeterminates. if we take F to correspond to the element in $B_4$ with exponents $(2,2)$ then we cannot achieve $2w_1+2w_2<w_1+3w_2$ and $2w_1+2w_2<3w_1+w_2$.


Same question for $n$-variables $x_1,\ldots, x_n$ and $k\geq n.$

Apologies if this question has been answered; (general and specific) references also appreciated.

$\endgroup$
  • $\begingroup$ This is a really interesting question and I'm going to start thinking about it. $\endgroup$ – Samuel Reid Nov 4 '13 at 4:50

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.