If you are looking for a post related to umbrellas, I'm sorry to say that the title of this post is highly misleading.
I've published an entry on ambiguity and Logic: More on ambiguity and logic
There is an umbrella in the illustration, and it mentions umbrellas towards the end, but that's as far as it goes with respect to umbrellas. Sorry again!
But maybe you'll find something interesting in the rest of the entry.