### Quadrature over Neighboring Elements within Finite Horizon, Where to Begin?

I've read the ufl documentation, but I'm still unsure of how to proceed with defining, say, bilinear forms using values of the unknown in neighboring elements. I understand that I can calculate the 'jump' between adjacent elements, but this is only one case I'm interested in.

I've also thumbed through the fenics book and ffc guide, but this hasn't helped significantly.

https://media.readthedocs.org/pdf/fenics-ufl/stable/fenics-ufl.pdf

Searching for ** integral equations in **Fenics seems to have been most helpful, as I came across these contributions:

integral equation:

https://www.mail-archive.com/fenics-support@fenicsproject.org/msg01286.html

composition:

https://fenicsproject.org/qa/7541/ufl-unsupported-operand-type-s-for-form-and-form/

other finds(ignore):

https://fenicsproject.org/qa/11007/petscmatrix-built-petsc4py-matrix-cannot-matvec-parallel/

https://fenicsproject.org/qa/8820/solving-pde-on-disconnected-meshes/

**If anyone could provide other useful examples to this end, I'd really appreciate it!**

(My apologies, I've made a few of these)