# subset 1 of (A..Z)
set_1 = (A, B, C, X, Y, Z)
# subset 2 of (a..z)
set_2 = (q, w, r, t, u)
# valid pairs
valid = ((A,q) = 1, (A,u) = 6, (A,k) => 3, (C,t) = 10, (Z,u) = 30)

##</code><code>##

my %INDEX = { 
    A => { q => 1, u => 6, k => 3 }, 
    C => { t => 10 }, 
    Z => { u => 30 }, 
    M => { q => 100 } 
}

##</code><code>##

# narrow by first set
(set_1) x (keys %INDEX) = (set_1) x (A, C, M, Z) = (A, C, Z)

##</code><code>##

set_2 x (q, u, k) + set_2 x (t) + set_2 x (u) = (1, 6, 10, 30)