Assignment #6

Note that Monday 2/17 is a holiday.

Assignment due in lecture on Friday, Feb. 21:

To do but not hand in:

V-3, V-6;

W-1 (below).

To hand in:

V-1, V-2, V-11(b), V-12;

X-10.

Problem W-1. In a polarity with context $(X, Y, \rho)$, show that any closed set $A$ in $X$ is the intersection of ``polars'' of singletons: $A = \cap _ {b \in B} \{b\} ^ \ell$ for some $B \subseteq Y$. Thus to find closed sets on one side it's enough to start with the singletons on the opposite side.