WWW.VIDYARTHIPLUS.COM
w
Design axioms and Corollaries.
OO Design Axioms
An axiom is a fundamental truth that always is observed to be valid and for which there
is no counterexample or exception.
The axioms cannot be proven or derived.
A theorem is a proposition that may not be self-evident but can be proven from accepted
axioms. Therefore, is equivalent to a law or principle.
A theorem is valid if its referent axioms & deductive steps are valid.
A corollary is a proposition that follows from an axiom or another proposition that has
been proven
Suh’s design axioms to OOD :
o Axiom 1 : The independence axiom. Maintain the independence of components
o Axiom 2 : The information axiom. Minimize the information content of the
design.
Axiom 1
States that, during the design process, as we go from requirement and use - case to a
system component, each component must satisfy that requirement, without affecting other
requirements
Axiom 2
Concerned with simplicity. Rely on a general rule known as Occam‟s razor.
Occam‟s razor rule of simplicity in OO terms :
The best designs usually involve the least complex code but not necessarily the fewest
number of classes or methods. Minimizing complexity should be the goal, because that produces
the most easily maintained and enhanced application. In an object-oriented system, the best way
to minimize complexity is to use inheritance and the system‟s built-in classes and to add as little
as possible to what already is there.
Corollaries
May be called Design rules , and all are derived from the two basic axioms :The origin of
collaries as shown in figure 2. Corollaries 1,2 and 3 are from both axioms, whereas corollary 4 is
from axiom 1 and corollaries 5 & 6 are from axiom 2.
