I don't know the term polivalent, but in general I agree that the edges and in-between spaces are often the most interesting. Being the practical sort, I think of thick doorways, lined with books or panels; windows recessed into thick walls, porches and patios as indoor/outdoor spaces, and the paths between garden beds rather than the beds themselves as a few examples. Too much architecture is essentially a piece of sculpture sitting in a field, or a collection of rooms all flowing into each other. (My own designs included.) 

It sounds like you're more academic in your approach--what is it that you find interesting about these types of spaces? 

I like turtles

What about the spaces in-between the in-between spaces?

here is everyone's favorite Slovenian philosopher on the subject: 

My thesis was based on the realm of the in-between. My teacher would keep asking me how I define an in-between space and that’s how my project evolved. So your first step would be to read texts by some important architects who have worked using that concept and you’ll be surprised at how differently this concept has been applied to big or small projects. I struggled to find what it meant to me but when I did, trust me it was so much fun exploring the idea. Look at precedences and identify what kind of an in between space that is, that’ll help you understand it deeper. For my thesis I looked at the micro yuaner library and Aberdeen city garden proposal, you can look them up for some ideas. So my argument was about how architects think about life within the buildings but rarely do we think about life between buildings , hence the underutilized sites and voids in our fabric were my main targets. There’s a pdf that’s available online based on the in between, give it a read - comparisons of in-between concepts by Aldo van eyck and kisho kurokawa -through theories of ‘twin phenomena’ and ‘symbiosis’. Read everything but the project will evolve from within you. Define it for yourself and take it from there.

shhhh... Gordon Matta-Clark was doing this long time.

Life Between Buildings google search should land you firmly in Gehl territory...

this is a perennial topic that gets a lot of academics wet. Have fun!

inbetween architecture:

http://www.architecturaldrawin...