I want to define an inequality constraint for a PYMC3 model. I found this post about defining an equality constraint (i.e., a+b1+b2=1) using pm.Potential. Does anyone know how to change that equality constraint into an inequality constraint like 0.9<a+b1+b2<1? Thanks! Answer The post you mention uses pm.math.eq which stands for “equal”. There are also pm.math.lt (lower than) and pm.math.le (lower