All of the state diagrams in Figure X7.21 are ambiguous. List all of the ambiguities in these state diagrams. (Hint: Use Karnaugh maps where necessary to find uncovered and double-covered input combinations. Or, if you have an HDL compiler or other logic minimizer available, you can write and minimize an expression for each state that is the AND of all the transition expressions leaving that state; the result is 1 for the input values that are double-covered. Similarly, write and minimize an expression for each state that is the NOR of all the transition expressions leaving that state; the result is I for the input values that are uncovered.)