http://hdl.handle.net/10174/1009 Sat, 31 Oct 2026 05:23:14 GMT 2026-10-31T05:23:14Z http://hdl.handle.net/10174/42713 Title: Local estimates for functionals rotationally invariant with respect to the gradient Authors: Santos, Telma João Abstract: This paper concerns minimization problems from Calculus of Variations rotationally invariant with respect to the gradient. Inspired by properties associated with results which are valid for elliptic partial differential equations, it presents some local estimates nearby non extremum points as well as nearby extremum points for these problems, generalizing some results obtained by Arrigo Cellina, Vladimir V. Goncharov and myself. As a consequence, some local estimates are obtained for the difference between the supremum and the infimum of any solution to the problem considered Thu, 29 Dec 2022 00:00:00 GMT http://hdl.handle.net/10174/42713 2022-12-29T00:00:00Z http://hdl.handle.net/10174/42198 Title: On the intersection of fixed subgroups of Fn × F m Authors: Carvalho, André Editors: Diekert, Volker Abstract: We prove that, although it is undecidable if a subgroup fixed by an automorphism intersects nontrivially an arbitrary subgroup of F n × F m , there is an algorithm that, taking as input a monomorphism and an endomorphism of F n × F m , decides whether their fixed subgroups intersect nontrivially. The general case of this problem, where two arbitrary endomorphisms are given as input, remains unknown. We show that, when two endomorphisms of a certain type are given as input, this problem is equivalent to the Post Correspondence Problem for free groups. Tue, 24 Feb 2026 00:00:00 GMT http://hdl.handle.net/10174/42198 2026-02-24T00:00:00Z http://hdl.handle.net/10174/41411 Title: Bridging meadows and sheaves Authors: Dias, João; Dinis, Bruno; Macias Marques, Pedro Abstract: We bridge sheaves of rings over a topological space with common meadows (algebraic structures where the inverse for multiplication is a total operation). More specifically, we show that, given a topological space X, the subclass of pre-meadows with a, coming from the lattice of open sets of X, and the class of presheaves over X are the same structure. Furthermore, we provide a construction that, given a sheaf of rings F on X, produces a common meadow as a disjoint union of elements of the form F(U) indexed over the open subsets of X. As a consequence, we see that the process of going from a presheaf to a sheaf (called sheafification) allows us to get a way to construct a common meadow from a given pre-meadow as above. Thu, 01 Jan 2026 00:00:00 GMT http://hdl.handle.net/10174/41411 2026-01-01T00:00:00Z http://hdl.handle.net/10174/41122 Title: Marginality scales for gradable adjectives Authors: Dinis, Bruno; Jacinto, Bruno Abstract: We propose the marginality scales account of the semantics of vague gradable adjectives, argue that this account is supported by Fara's interest-relative conception of vagueness, and show how this fact sheds new light on Dinis and Jacinto's nonstandard primitivism about vagueness -- a central feature of the marginality scales account. Nonstandard primitivism relies on the so-called ML theory. We also offer a significantly simplified version of this theory. Thu, 01 Jan 2026 00:00:00 GMT http://hdl.handle.net/10174/41122 2026-01-01T00:00:00Z