20294
The expression is non-unique : the manipulation of handlebody decompositions is an essential ingredient of the proof of the Smale h-cobordism theorem , and its generalization to the s-cobordism theorem .
 Smale
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Smale