This is complete non-sense:
- "Among the formal graphical methods are Frege's (1879) Begriffsschrift, Peirce's (1909) existential graphs, and Sowa's (1984) conceptual graphs. These three are based in first-order predicate logic."
(i) Frege's system is not a graphical method. It's a logical calculus; an axiomatic proof system.
(ii) Frege's 1879 Begriffsschrift is not "based in first-order logic". This not only false (it is *second*-order), and anachronistic (first-order logic was first singled out as a separate system by Hilbert and Ackermann in 1928), it's also completely ignoring the fact that Frege was the first to formulate predicate logic (second-order predicate logic, which is much stronger than, and includes, first-order logic) in this very work.