Changes

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That expresses the proposed equation in the language of logical graphs.  To test whether the equation holds we need to use the rest of the formal system that comes with this formal language, namely, a set of axioms taken for granted and a set of inference rules that allow us to derive the consequences of these axioms.

That expresses the proposed equation in the language of logical graphs.  To test whether the equation holds we need to use the rest of the formal system that comes with this formal language, namely, a set of axioms and a set of inference rules that allow us to derive the consequences of these axioms.