24. A computer program product embodied in a non-transitory computer readable medium for design simulation comprising: code for obtaining a high-level design which includes a word-level representation; code for obtaining a bit-level representation of the high-level design; code for determining a map between the word-level representation and the bit-level representation; code for optimizing the bit-level representation; and code for lifting results from the optimizing of the bit-level representation and including the results in the word-level representation based on the map wherein the lifting includes creating an isomorph of the bit-level representation within the word-level representation and where the creating an isomorph includes mapping bit-level nets to corresponding nets within the word-level representation where the bit-level nets are merged, identifying nets from the bit-level representation that are merged, and merging the corresponding nets within the word-level representation.
24. A computer program product embodied in a non-transitory computer readable medium for design simulation comprising: code for obtaining a high-level design which includes a word-level representation; code for obtaining a bit-level representation of the high-level design; code for determining a map between the word-level representation and the bit-level representation; code for optimizing the bit-level representation; and code for lifting results from the optimizing of the bit-level representation and including the results in the word-level representation based on the map wherein the lifting includes creating an isomorph of the bit-level representation within the word-level representation and where the creating an isomorph includes mapping bit-level nets to corresponding nets within the word-level representation where the bit-level nets are merged, identifying nets from the bit-level representation that are merged, and merging the corresponding nets within the word-level representation. 25. The computer program product of claim 24 further comprising code for maintaining the map between the word-level representation and the bit-level representation.