The positivity problem for fourth order linear recurrence sequences is decidable
Pinthira Tangsupphathawat, Narong Punnim, Vichian Laohakosol · Colloquium Mathematicum · 2012
The problem whether each element of a sequence satisfying a fourth order linear recurrence with integer coefficients is nonnegative, referred to as the Positivity Problem for fourth order linear recurrence sequence, is shown to be decidable.