We study invariants coming from certain optimisation problems for nef divisors on surfaces. These arise in work of the author and collaborators tying obstructions to embeddings between symplectic 4-manifolds questions positivity (possibly singular) algebraic develop general framework these prove foundational results their structure asymptotics. describe connections have embedded contact homolog...

we study algebraic properties of categories of merotopic, nearness, and filter algebras. we show that the category of filter torsion free abelian groups is an epireflective subcategory of the category of filter abelian groups. the forgetful functor from the category of filter rings to filter monoids is essentially algebraic and the forgetful functor from the category of filter groups to the cat...