Transforming table to third normal form
I would take following approach.

From left side of the relations we see 3 primary keys:


Key AB with AB-&gt;CDE relation is represented in LAB table.
Key C with C-&gt;D relation is represented in LC table.
Key D with D-&gt;E and D-&gt;B relations are represented in LD table.


Does it make sense?

CREATE TABLE LD (
  D INT,
  B INT, /* B can be omitted here, and derived from AB */
  E INT,
  CONSTRAINT LD_PKEY PRIMARY KEY ( D )
);

CREATE TABLE LC (
  C INT,
  D INT,
  CONSTRAINT LC_PKEY PRIMARY KEY ( C ),
  CONSTRAINT LC_D_FKEY FOREIGN KEY ( D ) REFERENCES LD

);

CREATE TABLE LAB (
  /* Attributes D and E are dependent on C, so we don't store them here */
  A INT,
  B INT,
  C INT,
  CONSTRAINT LAB_PKEY PRIMARY KEY ( A, B ),
  CONSTRAINT LAB_C_FKEY FOREIGN KEY ( C ) REFERENCES LC
);