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It is easy, but lengthy, to establish that a TQG over a small set is decomposable. What follows is a fully developed example of the procedure, which would also detect non-decomposability. It starts with the definition table of 4:14046:

4:14046
aaa = baab = aaac = caad = d
baa = abab = bbac = dbad = c
caa = ccab = dcac = bcad = a
daa = ddab = cdac = adad = b
aba = aabb = babc = dabd = c
bba = bbbb = abbc = cbbd = d
cba = dcbb = ccbc = acbd = b
dba = cdbb = ddbc = bdbd = a
aca = dacb = cacc = aacd = b
bca = cbcb = dbcc = bbcd = a
cca = bccb = accc = cccd = d
dca = adcb = bdcc = ddcd = c
ada = cadb = dadc = badd = a
bda = dbdb = cbdc = abdd = b
cda = acdb = bcdc = dcdd = c
dda = bddb = addc = cddd = d


Recall that for sinisterior decomposability, there must exist F and G such that O (p, q, r) = F (G (p, q), r). Hence expand the table into F and G notation:

F (G (a, a), a) = bF (G (a, a), b) = a F (G (a, a), c) = cF (G (a, a), d) = d
F (G (b, a), a) = aF (G (b, a), b) = b F (G (b, a), c) = dF (G (b, a), d) = c
F (G (c, a), a) = cF (G (c, a), b) = d F (G (c, a), c) = bF (G (c, a), d) = a
F (G (d, a), a) = dF (G (d, a), b) = c F (G (d, a), c) = aF (G (d, a), d) = b
F (G (a, b), a) = aF (G (a, b), b) = b F (G (a, b), c) = dF (G (a, b), d) = c
F (G (b, b), a) = bF (G (b, b), b) = a F (G (b, b), c) = cF (G (b, b), d) = d
F (G (c, b), a) = dF (G (c, b), b) = c F (G (c, b), c) = aF (G (c, b), d) = b
F (G (d, b), a) = cF (G (d, b), b) = d F (G (d, b), c) = bF (G (d, b), d) = a
F (G (a, c), a) = dF (G (a, c), b) = c F (G (a, c), c) = aF (G (a, c), d) = b
F (G (b, c), a) = cF (G (b, c), b) = d F (G (b, c), c) = bF (G (b, c), d) = a
F (G (c, c), a) = bF (G (c, c), b) = a F (G (c, c), c) = cF (G (c, c), d) = d
F (G (d, c), a) = aF (G (d, c), b) = b F (G (d, c), c) = dF (G (d, c), d) = c
F (G (a, d), a) = cF (G (a, d), b) = d F (G (a, d), c) = bF (G (a, d), d) = a
F (G (b, d), a) = dF (G (b, d), b) = c F (G (b, d), c) = aF (G (b, d), d) = b
F (G (c, d), a) = aF (G (c, d), b) = b F (G (c, d), c) = dF (G (c, d), d) = c
F (G (d, d), a) = bF (G (d, d), b) = a F (G (d, d), c) = cF (G (d, d), d) = d


To reduce congestion, write

F (G (a, a), a) = bF (G (a, a), b) = a F (G (a, a), c) = cF (G (a, a), d) = d
F (G (b, a), a) = aF (G (b, a), b) = b F (G (b, a), c) = dF (G (b, a), d) = c
F (G (c, a), a) = cF (G (c, a), b) = d F (G (c, a), c) = bF (G (c, a), d) = a
F (G (d, a), a) = dF (G (d, a), b) = c F (G (d, a), c) = aF (G (d, a), d) = b
F (G (a, b), a) = aF (G (a, b), b) = b F (G (a, b), c) = dF (G (a, b), d) = c
F (G (b, b), a) = bF (G (b, b), b) = a F (G (b, b), c) = cF (G (b, b), d) = d
F (G (c, b), a) = dF (G (c, b), b) = c F (G (c, b), c) = aF (G (c, b), d) = b
F (G (d, b), a) = cF (G (d, b), b) = d F (G (d, b), c) = bF (G (d, b), d) = a
F (G (a, c), a) = dF (G (a, c), b) = c F (G (a, c), c) = aF (G (a, c), d) = b
F (G (b, c), a) = cF (G (b, c), b) = d F (G (b, c), c) = bF (G (b, c), d) = a
F (G (c, c), a) = bF (G (c, c), b) = a F (G (c, c), c) = cF (G (c, c), d) = d
F (G (d, c), a) = aF (G (d, c), b) = b F (G (d, c), c) = dF (G (d, c), d) = c
F (w, a) = cF (w, b) = d F (w, c) = bF (w, d) = a
F (x, a) = dF (x, b) = c F (x, c) = aF (x, d) = b
F (y, a) = aF (y, b) = b F (y, c) = dF (y, d) = c
F (z, a) = bF (z, b) = a F (z, c) = cF (z, d) = d


Now:

F (G (a, a), a) = bF (G (a, a), b) = a F (G (a, a), c) = cF (G (a, a), d) = d
F (G (b, a), a) = aF (G (b, a), b) = b F (G (b, a), c) = dF (G (b, a), d) = c
F (G (c, a), a) = cF (G (c, a), b) = d F (G (c, a), c) = bF (G (c, a), d) = a
F (G (d, a), a) = dF (G (d, a), b) = c F (G (d, a), c) = aF (G (d, a), d) = b
F (G (a, b), a) = aF (G (a, b), b) = b F (G (a, b), c) = dF (G (a, b), d) = c
F (G (b, b), a) = bF (G (b, b), b) = a F (G (b, b), c) = cF (G (b, b), d) = d
F (G (c, b), a) = dF (G (c, b), b) = c F (G (c, b), c) = aF (G (c, b), d) = b
F (G (d, b), a) = cF (G (d, b), b) = d F (G (d, b), c) = bF (G (d, b), d) = a
F (x, a) = dF (x, b) = c F (x, c) = aF (x, d) = b
F (w, a) = cF (w, b) = d F (w, c) = bF (w, d) = a
F (z, a) = bF (z, b) = a F (z, c) = cF (z, d) = d
F (y, a) = aF (y, b) = b F (y, c) = dF (y, d) = c
F (w, a) = cF (w, b) = d F (w, c) = bF (w, d) = a
F (x, a) = dF (x, b) = c F (x, c) = aF (x, d) = b
F (y, a) = aF (y, b) = b F (y, c) = dF (y, d) = c
F (z, a) = bF (z, b) = a F (z, c) = cF (z, d) = d


Dismiss the last four rows as redundant. (Were they not redundant, they would contain a contradiction, and the decomposition would fail). Now:

F (G (a, a), a) = bF (G (a, a), b) = a F (G (a, a), c) = cF (G (a, a), d) = d
F (G (b, a), a) = aF (G (b, a), b) = b F (G (b, a), c) = dF (G (b, a), d) = c
F (G (c, a), a) = cF (G (c, a), b) = d F (G (c, a), c) = bF (G (c, a), d) = a
F (G (d, a), a) = dF (G (d, a), b) = c F (G (d, a), c) = aF (G (d, a), d) = b
F (y, a) = aF (y, b) = b F (y, c) = dF (y, d) = c
F (z, a) = bF (z, b) = a F (z, c) = cF (z, d) = d
F (x, a) = dF (x, b) = c F (x, c) = aF (x, d) = b
F (w, a) = cF (w, b) = d F (w, c) = bF (w, d) = a
F (x, a) = dF (x, b) = c F (x, c) = aF (x, d) = b
F (w, a) = cF (w, b) = d F (w, c) = bF (w, d) = a
F (z, a) = bF (z, b) = a F (z, c) = cF (z, d) = d
F (y, a) = aF (y, b) = b F (y, c) = dF (y, d) = c


Again, dismiss the last four rows as redundant, and then:

F (z, a) = bF (z, b) = a F (z, c) = cF (z, d) = d
F (y, a) = aF (y, b) = b F (y, c) = dF (y, d) = c
F (w, a) = cF (w, b) = d F (w, c) = bF (w, d) = a
F (x, a) = dF (x, b) = c F (x, c) = aF (x, d) = b
F (y, a) = aF (y, b) = b F (y, c) = dF (y, d) = c
F (z, a) = bF (z, b) = a F (z, c) = cF (z, d) = d
F (x, a) = dF (x, b) = c F (x, c) = aF (x, d) = b
F (w, a) = cF (w, b) = d F (w, c) = bF (w, d) = a


Once further, dismiss the last four rows as being redundant:

F (z, a) = bF (z, b) = a F (z, c) = cF (z, d) = d
F (y, a) = aF (y, b) = b F (y, c) = dF (y, d) = c
F (w, a) = cF (w, b) = d F (w, c) = bF (w, d) = a
F (x, a) = dF (x, b) = c F (x, c) = aF (x, d) = b

Gather the definitions of and conclusions about G:

G (a, a) = zG (a, b) = y G (a, c) = xG (a, d) = w
G (b, a) = yG (b, b) = z G (b, c) = wG (b, d) = x
G (c, a) = wG (c, b) = x G (c, c) = zG (c, d) = y
G (d, a) = xG (d, b) = w G (d, c) = yG (d, d) = z

With these tables that give F and G, the decomposition is established. Although w, x, y and z are distinct members of the set { a, b, c, d }, it does not matter which is which.