Locator Algebra (4)

Varbind, Varget
- to realize joins across contexts
- varbind[i,f]: L ? L, where i ? Name, f: PL ? Lvarbind[i,f](x):for all u ? x: vars(u):=vars(u) ? ?v?f(tail(u))<i,v>
- varget[i]: PL ? Lvarget[i](u): {v | (i,v) ? vars(u)}

Varbind, Varget