Apply Definition of MVD (multivalued dependency) to Example? Supposedly this multivalued dependency (MVD) and this functional dependency (FD):


  {W} ↠ {N,D} and {W} → {N}


hold in this table:


  V   W   N   D
=================
| v | w | n | 1 |
-----------------
| v | w | n | 2 |
-----------------



How do I show that this relation has those two dependencies via the following definition?


  Let R be a relational schema and let A ⊆ R and B ⊆ R (subsets). The multivalued dependency
  A ↠ B
  (which can be read as A multidetermines B) holds on R if, in any legal relation r(R), for all pairs of tuples t1 and t2 in r such that t1[A] = t2[A], there exist tuples t3 and t4 in r such that
  t1[A] = t2[A] = t3[A] = t4[A]
  t3[B] = t1[B]
  t3[R - B] = t2[R - B]
  t4[B] = t2[B]
  t4[R - B] = t1[R - B]
A FD is a MVD "in disguise". If an FD holds then a certain MVD also holds. With MVDs 1 is a special case of multi(ple). This can be seen from the rules of inference for MVDs at the definition link: RA → B implies A ↠ B.

Hint: t1 &amp; t2 can be t3 &amp; t4.

Hint: In the example there are only two tuples, so t1 &amp; t2 must be those, and you know the MVD so you know A &amp; B, and there are only two tuples, so if t3 &amp; t4 exist they must be those. So fill in the equations and see whether given those two tuples (t1 &amp; t2) there are also two tuples with the properties needed (t3 &amp; t4).