I am having a bit of trouble understanding the notations as they seem to be contradictory. At 3:31 it is assumed that theta_t is the equivalent of theta_i and e_c is the equivalent of e_j, yet it does not correspond with the rest. If c and i are the context and t and j are the target (as shown in other equations and course correction), then these equations can’t possibly be the equivalent of each other. It does not help, that the equations seem to be correct with the referenced papers. Can someone explain to me how is this possible or what is the correct notation if it is wrong?

Hey Kdudziak.

Welcome to the community.

Yes, you are right. One can get confused by the term being ‘symmetrical’ and being ‘equivalent’. But if you carefully observe what Prof Ng has tried to explain here is: He is putting forward a condition for being symmetrical as per the ‘existence of the words’ with the term ‘proximity’.

I have highlighted the points from the given lecture for you. But try reading all from the beginning.

Hey, thank you for the reply.

After more reading I gathered that symmetry in this case means that it does not matter much which word is which. As such the discrepancy in the papers came from this assumption being already made in the GloVe one. The lectures were merely trying to correspond to the papers with their notation. Still, this was a bit confusing as the notation change threw me off (especially with the clarifications) and there wasn’t much said to explain this change between the context and target word order before it occurred seemingly out of nowhere.

Hello, Kdudziak.

The course only provides the related basic concepts and as you move forward with other courses related to these core topics, the explanation will be more viable and clear.

If you still have doubts, then please post the query.

Please note that picking up the random word and the picking up the meaningful word will always throw different symmetry.