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When you analyze a program, you'll often ask yourself the questions:

1. What influences the value of this variable here?
2. What depends on the value of this variable?

data dependency:

there is a def-use influence from expression A to expression B if A defines a value used in B

control dependency:

there is a control influence from predicate A to expression B if A decides whether B is executed or not

  1:   a = 1;
  2:   if (a > 0) 
  3:     b = 1;
  4:   c = a;

Bauhaus computes all these influences for you and then allows you traverse these influences. This traversal is also known as program slicing.

backward slice:

follows backward all def-use and control influences; it gives you the answer to question 1

forward slice:

follows forward all def-use and control influences; it gives you the answer to question 2

The backward slice for the above example with respect to line 4 is:

  1:   a = 1;
  2:   
  3:   
  4:   c = a;