Vengono fornite alcune disuguaglianze cardinali relative a varie funzioni
cardinali definite in termini di certi ricoprimenti aperti. Tra l'altro
si prova che $\mid X\mid\leq e(X)^{\psi m(X)}$ e $\mid X\mid\leq wL(X)^{\psi u(X)}$
per ogni T$_{1}$-spazio x completamente regolare. Qui e (X), wL(X),
$\psi m(X)$ e $\psi u(X)$ denotano rispettivamente l'estensione,
il numero debole di Lindel$\ddot{\textrm{o}}$f. Some cardinal inequalities with cardinal functions defined in terms
of certain typed of covers are given. Among other results it is shown
that $\mid X\mid\leq e(X)^{\psi m(X)}$ and $\mid X\mid\leq wL(X)^{\psi u(X)}$
for any completely regular T$_{1}$-space x. Here e (X), wL(X), $\psi m(X)$
e $\psi u(X)$ denote respectively the extent, the weak Lindel$\ddot{\textrm{o}}$f
number, the pseudo-metrizability degree and the pseudo uniform weight
of X.
