Lorentz symmetry violation (LSV) can be generated at the Planck scale, or at
some other fundamental length scale, and naturally preserve Lorentz symmetry as
a low-energy limit (deformed Lorentz symmetry, DLS). DLS can have important
implications for ultra-high energy cosmic-ray physics (see papers
physics/0003080, astro-ph/0011181 and astro-ph/0011182, and references quoted
in these papers). A crucial question is how DLS can be extended to a deformed
Poincare symmetry (DPS), and what can be the dynamical origin of this
phenomenon. We discuss recent proposals to identify DPS with a symmetry
incorporating the Planck scale (doubly special relativity, DSR) and suggest new
ways in this direction. Implications for models of quadratically deformed
relativistic kinematics (QDRK) and linearly deformed relativistic kinematics
(LDRK) are also discussed.Comment: 9 pages, updated comment to three contributions to the ICRC 2001
Conferenc
