Bogomolov multiplier of groups

‎Let $G$ be a finite group and the Bogomolov multiplier $B_0(G)$ of $G$ is defined as the subgroup of the Schur multiplier $H^2(G,{\Bbb{Q}}/{\Bbb{Z}})$ consisting of the cohomology classes whose restriction to all abelian subgroups of $G$ are zero‎. ‎The triviality of the Bogomolov multiplier is an obstruction to classical Noether s problem over $\Bbb{C}$‎. ‎After introduce the concept‎ ‎curly exterior product ‎, ‎Moravec in [4] recomends a new definition for Bogomolov multiplier and here‎, ‎we show some properties of curly exterior product of groups‎, ‎describe Bogomolov multiplier for $2$-generator $p$-groups of nilpotency class $2$ and also‎, ‎classify all non abelian groups of order $p^7$ and exponent $p$ with trivial Bogomolov multiplier for any prime $p 3$‎.