We study the problem of conformal deformation of Riemannian structure to constant scalar curvature with zero mean curvature on the boundary. We prove compactness for the full set of solutions when the boundary is umbilic and the dimension n ≤ 24. The Weyl Vanishing Theorem is also established under these hypotheses, and we provide counter-examples to compactness when n ≥ 25. Lastly, our methods...

In this paper, using the maximal element theorem, we prove some existence theorem for vector quasi-variational-like inequalities without monotonicity and without compactness.

We present some model theoretic results for {L}ukasiewiczpredicate logic by using the methods of continuous model theorydeveloped by Chang and Keisler.We prove compactness theorem with respect to the class of allstructures taking values in the {L}ukasiewicz $texttt{BL}$-algebra.We also prove some appropriate preservation theorems concerning universal and inductive theories.Finally, Skolemizatio...

A useful compactness theorem for constraint satisfaction problems is proved equivalent to BPI, the Boolean Prime Ideal Theorem. The relation of various restricted versions of the Theorem to each other and to BPI is also explored.