dorsal/arxiv
View SchemaOn consistency around a $3 \times 3\times 3$ cube and Q3 analogue of the lattice Boussinesq equation
| Authors | Pengyu Sun, Cheng Zhang, Frank Nijhoff |
|---|---|
| Categories | |
| ArXiv ID | 2601.05565vv1 |
| URL | https://arxiv.org/abs/2601.05565 |
| License | http://creativecommons.org/licenses/by/4.0/ |
Abstract
In this paper, we present two new aspects of lattice Boussinesq (BSQ) equations. First, we show that the lattice potential BSQ (lpBSQ) equation defined on a nine-point square lattice admits a natural extension of three-dimensional consistency to a $3\times 3\times 3$ cube\textemdash a cubic sublattice consisting of $27$ vertices. This extends the standard notion of three-dimensional consistency (defined on an elementary $2\times 2\times 2$ vertex cube for quadrilateral equations) to the non-quadrilateral, nine-point setting. Second, we construct a new three-component system which is referred to as the {\em lattice BSQ-Q3 system}, serving as the BSQ analogue of the Q3($\delta$) equation in the Adler-Bobenko-Suris (ABS) classification. The construction relies on a gauge transformation between Lax pairs of lpBSQ with the parameter $\delta$ arising from a $GL_3$ action. In a degeneration form, the system yields a $PGL_3$-invariant integrable lattice equation that generalises the $PGL_2$-invariant Schwarzian BSQ equation.
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"abstract": "In this paper, we present two new aspects of lattice Boussinesq (BSQ) equations. First, we show that the lattice potential BSQ (lpBSQ) equation defined on a nine-point square lattice admits a natural extension of three-dimensional consistency to a $3\\times 3\\times 3$ cube\\textemdash a cubic sublattice consisting of $27$ vertices. This extends the standard notion of three-dimensional consistency (defined on an elementary $2\\times 2\\times 2$ vertex cube for quadrilateral equations) to the non-quadrilateral, nine-point setting. Second, we construct a new three-component system which is referred to as the {\\em lattice BSQ-Q3 system}, serving as the BSQ analogue of the Q3($\\delta$) equation in the Adler-Bobenko-Suris (ABS) classification. The construction relies on a gauge transformation between Lax pairs of lpBSQ with the parameter $\\delta$ arising from a $GL_3$ action. In a degeneration form, the system yields a $PGL_3$-invariant integrable lattice equation that generalises the $PGL_2$-invariant Schwarzian BSQ equation.",
"arxiv_id": "2601.05565",
"authors": [
"Pengyu Sun",
"Cheng Zhang",
"Frank Nijhoff"
],
"categories": [
"nlin.SI",
"math-ph",
"math.MP"
],
"license": "http://creativecommons.org/licenses/by/4.0/",
"title": "On consistency around a $3 \\times 3\\times 3$ cube and Q3 analogue of the lattice Boussinesq equation",
"url": "https://arxiv.org/abs/2601.05565",
"version": "v1"
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