The display above is a variational inequality. Written as “solve on an unknown region with on its boundary”, it is a free-boundary problem: the boundary is part of the solution. The extra condition that fixes it, on where is smooth, is smooth pasting (or smooth fit).
Quantitative Finance · Glosario
¿Qué es Variational inequality, free-boundary problem, smooth pasting?
También llamado: variational inequality · free-boundary problem · smooth pasting