I am reading 'Finite Packing and Covering' and I find some notations on the first few pages that are not defined in the book. I am guessing those are standard in the discussion of packing problems. As I cannot find similar discussion on the Internet, I would like to see if anyone can clear my confusion.
Let $K$ be a convex domain. ( I guess it means a convex body? ) Given an arrangement of congruent copies of $K$ that is periodic with respect to some lattice $\Lambda$ and given $m$ equivalence classes (what equivalence classes are we talking about? ), it is natural to call $m \cdot A(K) / \det \Lambda$ the density of the arrangement. (What is $A(K)$? )
... We define $\Delta(K)=A(K)/\delta(K)$, where $\delta(K)$ is the packing density. (What is the meaning of this $\Delta(K)$?)
Any help would be appreciated.