In doing the Duo. Esperanto Home topic, I came across this sentence about 
a knife being a tool for cutting. I used tranĉa and was corrected in that 
it should be tranĉi, which I "thought" was the verb meaning 'to cut'.
So am I to assume that "tranĉi" means to cut as well as cutting.?
The sentence being...a knife is a tool for cutting.