Definition
Primary factor augmenting variable, denoted as AFE.
The percentage change of AFE equals 
in CES function (δ and β are different notion of share parameters, hat refers to percentage change)
Effects of AFE increases
- reduce demand for endowment at constant price
- reduce effective price for the endowment, encouraging factor substitution (using more of the input with higher AFE, and less of other inputs)
- lowers cost of value-added, encouraging expansion