Elias Humberto Alves, Brazilian logician and philosopher (Guaranésia, Minas Gerais State 17 February 1936 – São Paulo 04 November 2013)
Demonstrated the independence of axioms of the propositional calculus C1 axioms (1976)
Introduced the first systems of natural deduction for the logics Cn
Developed higher-order versions of Da Costa paraconsistent predicate logics
Solved definitely the problem of the decidability of logics Cn based on the semantics of quasi-matrices (1976)
Demonstrated the decidability of the propositional logics Cn (1976)
With A. Loparic modified certain conditions in valuation definition (1980)
With A. Loparic introduced a bivalent semantics and a decision method for Da Costa logics Cω (1980)
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