  Prompt {\gamma}-ray emissions from gamma-ray bursts (GRBs) exhibit a vast
range of extremely complex temporal structures with a typical variability
time-scale significantly short - as fast as milliseconds. This work aims to
investigate the apparent randomness of the GRB time profiles making extensive
use of nonlinear techniques combining the advanced spectral method of the
Singular Spectrum Analysis (SSA) with the classical tools provided by the Chaos
Theory. Despite their morphological complexity, we detect evidence of a non
stochastic short-term variability during the overall burst duration - seemingly
consistent with a chaotic behavior. The phase space portrait of such
variability shows the existence of a well-defined strange attractor underlying
the erratic prompt emission structures. This scenario can shed new light on the
ultra-relativistic processes believed to take place in GRB explosions and
usually associated with the birth of a fast-spinning magnetar or accretion of
matter onto a newly formed black hole.
