Skip to main content

All Questions

Filter by
Sorted by
Tagged with
16 votes
1 answer
3k views

How do I see the equality $57 = 3 \times 19$ geometrically?

Consider the finite field ${\bf F}_p$ and its cubic extension ${\bf F}_{p^3}$. The multiplicative group ${\bf G}_m({\bf F}_{p^3})$ contains the multiplicative group ${\bf G}_m({\bf F}_p) \cong {\bf Z}/...
gulag57's user avatar
  • 364
10 votes
2 answers
495 views

Is there a hyperplane avoiding two independent sets?

Let $V$ be a vector space over a field with $5$ elements, $A,B \subseteq V$ independent subsets. Must there be a subspace of $V$ of codimension 1 disjoint from $A \cup B$?
Pablo's user avatar
  • 11.3k
6 votes
1 answer
303 views

Maximum number of elements in union of subspaces

Let $V$ be a $m$-dimensional vector space over $\mathbb{F}_q$ and $1<\ell<m-1$. Let $r$ be a positive integer such that $r\ell\leq m$. QUESTION. What is the maximum number of elements in the ...
user100393's user avatar
4 votes
1 answer
385 views

Point-Hyperplane incidence in finite projective spaces

Let $P$ be a finite projective space of order $q$ and dimension $d$. I am interested in finding the least $k$ such that for any set $S$ of $k$ points of $P$, and for any set $S'$ of $k$ hyperplanes of ...
Louis Esperet's user avatar