I've been trying to solve this question
In a lattice if $a≤b≤c$, show that (i)$a⊕b=b*c$ (ii)$(a*b)⊕(b*c)=(a⊕b)*(a⊕c)=b$
for a while now but I simply can't find anything even remotely related to this question. I've asked a couple of my friends about this as well and they say this is a theorem but can't remember its name. I don't want the direct answer (which, by the way is fine), just the name of the theorem if possible.