[plt-scheme] The perfect teaching language--Is this too much to ask for?

On Jun 15, 2009, at 2:40 PM, Arthur Nunes-Harwit wrote:
> While Russell & Whitehead's theory to avoid the paradox involved a  
> hierarchy, the set theories that were widely embraced (eg Zermelo- 
> Fraenkel and von_Neumann-Bernays-Goedel) had little or no hierarchy.

Russell & Whitehead's hierarchical approach failed; Goedel showed a  
way around any such system if you've got enough arithmetic to encode  
proofs about numbers as numbers.  I don't remember exactly how vNBG  
or ZF get around this.

Stephen Bloch
sbloch at adelphi.edu