The considerations of patterning are especially complicated in segmenting phonemic sequences which cannot be matched with other, partially identical, sequences. For example, if we consider 'run' in 'I’ll — over for it', we can substitute 'walk', 'stay', etc., and may thus set up each of these phoneme sequences as a morphemic segment. If we consider 'walked' in 'I — over before you came', we can substitute 'stayed', 'ran', etc. We can separate the '–ed' morphemically by setting up the environment 'I —ed over before you came', in which 'walk', 'stay', etc. replace each other. This does not enable us to segment 'ran'. However, we may analyze 'ran' on the basis of 'walked', 'stayed': since 'ran' substitutes for 'walked', etc., and 'run' for 'walk', etc., and since 'walked' has been segmented into 'walk' and 'ed', we may segment 'ran' into 'run' and /Ə/ → /æ/ (replacement of /Ə/ by /æ/).
- Harris (1951), Pag. 181