Questions

Use the concept of register-retiming.

divide the totla combinatorial delay in two segments such that individually the delay is less the clock period.

this can be done by inserting a flip-flop in the combinational path.

e.g.,

clock period --- 5 ns

total cominational delay ---- 7

then divide the 7ns path in two path of 4 or 3 (best resutls are obtained if delays are  same for both path i.e 3.5ns) by inserting a flip-flop in between.

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Hence, the term hierarchy refers to a power structure in which each member knows his or her own place.