  The theory of degree growth and algebraic entropy plays a crucial role in the
field of discrete integrable systems. However, a general method for calculating
degree growth for lattice equations (partial difference equations) is not yet
known. Here we propose a new method to rigorously compute the exact degree of
each iterate for lattice equations. Our strategy is to extend Halburd's method,
which is a novel approach to computing the exact degree of each iterate for
mappings (ordinary difference equations) from the singularity structure, to
lattice equations. First, we illustrate, without rigorous discussion, how to
calculate degrees for lattice equations using the lattice version of Halburd's
method and discuss what problems we need to solve to make the method rigorous.
We then provide a framework to ensure that all calculations are accurate and
rigorous. We also discuss how to detect the singularity structure of a lattice
equation. Our method is not only accurate and rigorous but also can easily be
applied to a wide range of lattice equations.
