**This is an old revision of the document!**

# Michael Collins, Nigel Duffy: Convolution kernels for natural language

### Questions

- What is a generative model, what is a discriminative model and what is their main difference?
- What are the “fairly strong independence assumptions” in PCFG? Come up with an example tree that can't be modelled by a PCFG.
- Derive and explain the formula for h(T1)*h(T2) on page 3 at the bottom.
- What is a convolution? Why are “convolution” kernels called like this?
- Find an error in one of the formulae in the paper.