‎let $g$ be a finite group and $d_2(g)$ denotes the probability ‎that $[x,y,y]=1$ for randomly chosen elements $x,y$ of $g$‎. ‎we ‎will obtain lower and upper bounds for $d_2(g)$ in the case where ‎the sets $e_g(x)={yin g:[y,x,x]=1}$ are subgroups of $g$ for ‎all $xin g$‎. ‎also the given examples illustrate that all the ‎bounds are sharp.

‎let $g$ be a finite group and $d_2(g)$ denotes the probability‎ ‎that $[x,y,y]=1$ for randomly chosen elements $x,y$ of $g$‎. ‎we‎ ‎will obtain lower and upper bounds for $d_2(g)$ in the case where‎ ‎the sets $e_g(x)={yin g:[y,x,x]=1}$ are subgroups of $g$ for‎ ‎all $xin g$‎. ‎also the given examples illustrate that all the‎ ‎bounds are sharp‎.

A normal projective variety X is called Fano if a multiple of the anticanonical Weil divisor, −KX , is an ample Cartier divisor. The importance of Fano varieties is twofold, from one side they give, has predicted by Fano [Fa], examples of non rational varieties having plurigenera and irregularity all zero (cfr [Is]); on the other hand they should be the building block of uniruled variety. Indee...

For a locally compact group G we look at the group algebras C 0 (G) and C * r (G), and we let f ∈ C 0 (G) act on L 2 (G) by the multiplication operator M (f). We show among other things that the following properties are equivalent: 1. G has a compact open subgroup. 2. One of the C *-algebras has a dense multiplier Hopf *-subalg-ebra (which turns out to be unique). 3. There are non-zero elements...