Possible Duplicate:
Can we categorify the equation (1 - t)(1 + t + t^2 + …) = 1?

Can you give a categorification of the geometric series identity: $$1/(1-x)=1+x+x^2+...$$ Categorifications of partial sum identities $$(1-x^{n+1})/(1-x)=1+x+x^2+...+x^n$$ would also be nice.

Can you give a categorification of the geometric series identity: $$1/(1-x)=1+x+x^2+...$$ Categorifications of partial sum identities $$(1-x^{n+1})/(1-x)=1+x+x^2+...+x^n$$ would also be nice.