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DISCUSSION 



Platt: Simon (48) has shown that skewed distributions (Yule distributions), such as those 

 in Fig. 2, can be obtained from models based on probabiHty assumptions much weaker than 

 those we were looking for. Thus our inability to determine constraints from a study of the 

 distribution of amino acid and letter frequencies in proteins and words is not surprising. 

 However (in agreement with our summarizing statement for that section), Simon points out 

 that the occurrence of a Yule distribution does not obviate more stringent constraints as the 

 underlying probability mechanism. 



