Operads are a specific tool for encoding type of algebras. For instance there are operads encoding associative algebras, commutative and associative algebras, Lie algebras, pre-Lie algebras, dendriform algebras, Poisson algebras and so on. A usual way of describing a type of algebras is by giving the generating operations and the relations among them. For instance a Lie algebra L is a vector sp...

This paper is a sequel to [12]. We are here concerned with properties of theories in full first-order intuitionistic logic; the latter correspond under the identification of theories with categories provided by categorical logic (cf. [8] or [ 1 l]), to Heyting pretoposes, i.e. pretoposes with universal quantification of subobjects along morphisms. Using the lattice-theoretic machinery developed...

Abstract. The normal symmetric triality algebras (STA’s) and the normal Lie related triple algebras (LRTA’s) have been recently introduced by the second author, in connection with the principle of triality. It turns out that the unital normal LRTA’s are precisely the structurable algebras extensively studied by Allison. It will be shown that the normal STA’s (respectively LRTA’s) are the algebr...

In 1938, Tarski proved that a formula is not intuitionistically valid if, and only if, it has a counter-model in the Heyting algebra of open sets of some topological space. In fact, Tarski showed that any Euclidean space Rn with n > 1 suffices, as does e.g. the Cantor space. In particular, intuitionistic logic cannot detect topological dimension in the frame of all open sets of a Euclidean spac...