arXiv subjects

K. V. Kaipa

Publications and source records attributed to K. V. Kaipa.

3 recordsLinked to original sources

arXiv2012

Weight spectrum of codes associated with the Grassmannian G(3,7)

In this paper we consider the problem of determining the weight spectrum of q-ary codes C(3,m) associated with Grassmann varieties G(3,m). For m=6 this was done by Nogin. We derive a formula for the weight of a codeword of C(3,m), in terms of certain varieties associated with alternating trilinear forms on (F_q)^m. The classification of such forms under the action of the general linear group GL(m,F_q) is the other component that is required to calculate the spectrum of C(3,m). For m=7, we explicitly determine the varieties mentioned above. The classification problem for alternating 3-forms on (F_q)^7 was solved by Cohen and Helminck, which we then use to determine the spectrum of C(3,7).

cs.IT↗

arXiv2009

Multiscale limit for finite-gap Sine-Gordon Solutions and Calculation of Topological Charge using Theta-functional Formulae

In this paper, we introduce the so-called multiscale limit for spectral curves, associated with real finite-gap Sine-Gordon solutions. This technique allows to solve the old problem of calculating the density of topological charge for real finite-gap Sine-Gordon solutions directly from the $θ$-functional formulas.

math-ph↗

arXiv2009

Calculation of Topological Charge of Real Finite-Gap sine-Gordon solutions using Theta-functional formulae

The most basic characteristic of x-quasiperiodic solutions u(x,t) of the sine-Gordon equation u_{tt}-u_{xx}+\sin u=0 is the topological charge density denoted $\bar n$. The real finite-gap solutions u(x,t) are expressed in terms of the Riemann theta-functions of a non-singular hyperelliptic curve $Γ$ and a positive generic divisor D of degree g on $Γ$, where the spectral data $(Γ, D)$ must satisfy some reality conditions. The problem addressed in note is: to calculate $\bar n$ directly from the theta-functional expressions for the solution u(x,t). The problem is solved here by introducing what we call the multiscale or elliptic limit of real finite-gap sine-Gordon solutions. We deform the spectral curve to a singular curve, for which the calculation of topological charges reduces to two special easier cases.

math-ph↗