How to determine if a database schema violates one of the less known normal forms?
From Wikipedia:


  1NF: The table faithfully represents a relation and has no repeating
  groups.
  
  2NF: Non-prime attributes are non functionally dependent on a proper
  subset of a candidate key.
  
  3NF: Non-prime attributes are non-transitively dependent on every
  candidate key in the table.
  
  BCNF: Every non-trivial functional dependency is a dependency on a
  superkey.
  
  4NF: Every non-trivial multivalued dependency in the table is a
  dependency on a superkey.
  
  5NF: Every non-trivial join dependency in the table is implied by the
  superkeys of the table.
  
  DKNF: Every constraint in the table is a logical consequence of the
  table's domain and key constraints.


Please let me know which, if any, of these requires further explanation. Each provides a means of checking whether a table is in the normal form.

EDIT: Again from Wikipedia:


  A join dependency is a constraint on the set of legal relations over a
  database scheme. A table $T$ is subject to a join dependency if $T$
  can always be recreated by joining multiple tables each having a
  subset of the attributes of $T$. If one of the tables in the join has
  all the attributes of the table $T$, the join dependency is called
  trivial.
  
  The join dependency plays an important role in the Fifth normal form,
  also known as project-join normal form, because it can be proven that
  if you decompose a scheme $R$ in tables $R_1$ to $R_n$, the
  decomposition will be a lossless-join decomposition if you restrict
  the legal relations on $R$ to a join dependency on $R$ called
  $*(R_1,R_2,...R_n)$.


In other words, if a constraint on your table $T$ is that T = R JOIN S for some tables $R$ and $S$, then $T$ has a join dependency $*(R, S)$.