why amsmath as default ?

[cghan]

Hello,

In the book layout style, lyx seems to use amsmath (via, i.e., 
\usepackage{amsmath}) whenever document contains equations(in-line, or 
display style equations). Is this feature intended, or a bug ? I use 
lyx-1.2.0cvs. 

The reason why I ask this queation is that I cannot break multi-line 
equations in amsmath style. Can anybody teach me how to break multi-line 
equations in amsmath?

Thank you for help,



--cghan