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We formulate an Algebraic-Coding Equivalence to the Maximum Distance Separable Conjecture. Specifically, we present novel proofs of the following equivalent statements. Let $(q,k)$ be a fixed pair of integers satisfying $q$ is a prime power and $2leq k leq q$. We denote by $mathcal{P}_q$ the vector space of functions from a finite field $mathbb{F}_q$ to itself, which can be represented as the space $mathcal{P}_q := mathbb{F}_q[x]/(x^q-x)$ of polynomial functions. We denote by $mathcal{O}_n subset mathcal{P}_q$ the set of polynomials that are either the zero polynomial, or have at most $n$ distinct roots in $mathbb{F}_q$. Given two subspaces $Y,Z$ of $mathcal{P}_q$, we denote by $langle Y,Z rangle$ their span. We prove that the following are equivalent. [A] Suppose that either: 1. $q$ is odd 2. $q$ is even and $k otin {3, q-1}$. Then there do not exist distinct subspaces $Y$ and $Z$ of $mathcal{P}_q$ such that: 3. $dim(langle Y, Z rangle) = k$ 4. $dim(Y) = dim(Z) = k-1$. 5. $langle Y, Z rangle subset mathcal{O}_{k-1}$ 6. $Y, Z subset mathcal{O}_{k-2}$ 7. $Ycap Z subset mathcal{O}_{k-3}$. [B] Suppose $q$ is odd, or, if $q$ is even, $k otin {3, q-1}$. There is no integer $s$ with $q geq s > k$ such that the Reed-Solomon code $mathcal{R}$ over $mathbb{F}_q$ of dimension $s$ can have $s-k+2$ columns $mathcal{B} = {b_1,ldots,b_{s-k+2}}$ added to it, such that: 8. Any $s times s$ submatrix of $mathcal{R} cup mathcal{B}$ containing the first $s-k$ columns of $mathcal{B}$ is independent. 9. $mathcal{B} cup {[0,0,ldots,0,1]}$ is independent. [C] The MDS conjecture is true for the given $(q,k)$.
Given any linear code $C$ over a finite field $GF(q)$ we show how $C$ can be described in a transparent and geometrical way by using the associated Bruen-Silverman code. Then, specializing to the case of MDS codes we use our new approach to offer improvements to the main results currently available concerning MDS extensions of linear MDS codes. We also sharply limit the possibilities for constructing long non-linear MDS codes.
The graph reconstruction conjecture asserts that every finite simple graph on at least three vertices can be reconstructed up to isomorphism from its deck - the collection of its vertex-deleted subgraphs. Kocays Lemma is an important tool in graph reconstruction. Roughly speaking, given the deck of a graph $G$ and any finite sequence of graphs, it gives a linear constraint that every reconstruction of $G$ must satisfy. Let $psi(n)$ be the number of distinct (mutually non-isomorphic) graphs on $n$ vertices, and let $d(n)$ be the number of distinct decks that can be constructed from these graphs. Then the difference $psi(n) - d(n)$ measures how many graphs cannot be reconstructed from their decks. In particular, the graph reconstruction conjecture is true for $n$-vertex graphs if and only if $psi(n) = d(n)$. We give a framework based on Kocays lemma to study this discrepancy. We prove that if $M$ is a matrix of covering numbers of graphs by sequences of graphs, then $d(n) geq mathsf{rank}_mathbb{R}(M)$. In particular, all $n$-vertex graphs are reconstructible if one such matrix has rank $psi(n)$. To complement this result, we prove that it is possible to choose a family of sequences of graphs such that the corresponding matrix $M$ of covering numbers satisfies $d(n) = mathsf{rank}_mathbb{R}(M)$.
A conjecture of Hirschowitzs predicts that a globally generated vector bundle $W$ on a compact complex manifold $A$ satisfies the formal principle, i.e., the formal neighborhood of its zero section determines the germ of neighborhoods in the underlying complex manifold of the vector bundle $W$. By applying Cartans equivalence method to a suitable differential system on the universal family of the Douady space of the complex manifold, we prove that this conjecture is true if $A$ is a Fano manifold, or if the global sections of $W$ separate points of $A$. Our method shows more generally that for any unobstructed compact submanifold $A$ in a complex manifold, if the normal bundle is globally generated and its sections separate points of $A$, then a sufficiently general deformation of $A$ satisfies the formal principle. In particular, a sufficiently general smooth free rational curve on a complex manifold satisfies the formal principle.
We extend the equivalence between network coding and index coding by Effros, El Rouayheb, and Langberg to the secure communication setting in the presence of an eavesdropper. Specifically, we show that the most gener
The Collatz conjecture is explored using polynomials based on a binary numeral system. It is shown that the degree of the polynomials, on average, decreases after a finite number of steps of the Collatz operation, which provides a weak proof of the conjecture by using induction with respect to the degree of the polynomials.