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Inserted key proviso: containts a *nonzero* element
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Noam D. Elkies
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Let $E$ be a linear subspace of ${\bigwedge}^2({\mathbb R}^n)$. What is the minimal dimension of $E$ that guarantees $E$ contains ana nonzero element of the form $X\wedge Y$, with $X, Y\in{\mathbb R}^n$?

When $n=3$, dimension $1$ is enough. When $n=4$ we would need dimension $4$. For general $n$, it is easy to see $E$ having dimension $\frac{(n-1)(n-2)}{2}+1$ is sufficient, but I don't know if that is optimal.

Let $E$ be a linear subspace of ${\bigwedge}^2({\mathbb R}^n)$. What is the minimal dimension of $E$ that guarantees $E$ contains an element of the form $X\wedge Y$, with $X, Y\in{\mathbb R}^n$?

When $n=3$, dimension $1$ is enough. When $n=4$ we would need dimension $4$. For general $n$, it is easy to see $E$ having dimension $\frac{(n-1)(n-2)}{2}+1$ is sufficient, but I don't know if that is optimal.

Let $E$ be a linear subspace of ${\bigwedge}^2({\mathbb R}^n)$. What is the minimal dimension of $E$ that guarantees $E$ contains a nonzero element of the form $X\wedge Y$, with $X, Y\in{\mathbb R}^n$?

When $n=3$, dimension $1$ is enough. When $n=4$ we would need dimension $4$. For general $n$, it is easy to see $E$ having dimension $\frac{(n-1)(n-2)}{2}+1$ is sufficient, but I don't know if that is optimal.

\wedge -> \bigwedge
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LSpice
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A question about subspace in $\wedge^2${\bigwedge}^2({\mathbb R}^n)$

Let $E$ be a linear subspace of $\wedge^2({\mathbb R}^n)$${\bigwedge}^2({\mathbb R}^n)$. What is the minimal dimension of $E$ that guarantees $E$ contains an element of the form $X\wedge Y$, with $X, Y\in{\mathbb R}^n$?

When $n=3$, dimension 1$1$ is enough. When $n=4$ we would need dimension $4$. For general $n$, it is easy to see $E$ having dimension $\frac{(n-1)(n-2)}{2}+1$ is sufficient, but I don't know if that is optimal.

A question about subspace in $\wedge^2({\mathbb R}^n)$

Let $E$ be a linear subspace of $\wedge^2({\mathbb R}^n)$. What is the minimal dimension of $E$ that guarantees $E$ contains an element of the form $X\wedge Y$, with $X, Y\in{\mathbb R}^n$?

When $n=3$, dimension 1 is enough. When $n=4$ we would need dimension $4$. For general $n$, it is easy to see $E$ having dimension $\frac{(n-1)(n-2)}{2}+1$ is sufficient, but I don't know if that is optimal.

A question about subspace in ${\bigwedge}^2({\mathbb R}^n)$

Let $E$ be a linear subspace of ${\bigwedge}^2({\mathbb R}^n)$. What is the minimal dimension of $E$ that guarantees $E$ contains an element of the form $X\wedge Y$, with $X, Y\in{\mathbb R}^n$?

When $n=3$, dimension $1$ is enough. When $n=4$ we would need dimension $4$. For general $n$, it is easy to see $E$ having dimension $\frac{(n-1)(n-2)}{2}+1$ is sufficient, but I don't know if that is optimal.

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YCor
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Yuval
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