00:01
So we have two posets here, we want to see what additional structure they have.
00:05
Whether they're lattice, complemented lattice, or boolean algebras.
00:11
Something we see here, they are actually both lattices.
00:15
It's a bit tedious to verify this, but you can do it through brute force or just kind of by eyeballing it.
00:22
You see for example d and f join at a and meet at g.
00:27
E and c also join at a and meet at g, and so on and so forth.
00:33
B, it's a little bit harder to see that it is a lattice, but it is in fact still a lattice.
00:38
D and g for instance join not till a and meet at h.
00:46
Is that right? that is right.
00:51
That's good, they are both lattices and we can check that through brute force.
00:55
Are they complemented lattices though? i'm going to claim that no they are not.
01:00
For example, in part a, what would be the complement of d? well if we do the meets here, a and d of course meet at a, as do c and b, which is good.
01:13
E, f, and g each though meet at d because they are less than d.
01:18
And their joins, excuse me, those are the joins, i always get this mixed up.
01:24
The meets, a and d meet at d.
01:28
C and b respectively at f join respectively to f and f at e...