The Kardar-Parisi-Zhang (KPZ) equation is a paradigm of generic scale
invariance, for which it represents a conspicuous universality class. Recently,
the tensionless case of this equation has been shown to provide a different
universality class by itself. This class describes the -- intrinsically
anomalous -- scaling of one-dimensional (1D) fronts for several physical
systems that feature ballistic dynamics. In this work, we show that the
evolution of certain 1D fronts defined for a 2D Ising system also belongs to
the tensionless KPZ universality class. Nevertheless, the Ising fronts exhibit
multiscaling, at variance with the continuous equation. The discrete nature of
these fronts provides an alternative approach to assess the dynamics for the 2D
front case (for a 3D Ising system), since the direct integration of the
tensionless KPZ equation blows up in this case. In spite of the agreement
between the 1D scaling of the Ising fronts and the tensionless KPZ equation,
the fluctuation statistics in 1D and the full behavior in 2D are strongly
conditioned by boundary effects.Comment: 9 pages, 9 figure