How to view the optimized combinational function after HDL synthesis?
So I am not going to read the whole manual.  But, from 

XST manual

There is the option for "-rtlview yes", which tells XST to generate a netlist file representing the RTL structure of the design.

Direct quote: "You can also set this value in ISE® Design Suite in Process>Properties>Synthesis Options>Generate RTL Schematic."

There might be an option to print each reduced equation, but I cannot find it (I tried searching 'print' and 'equations', but there was no joy).