Pietz, AndreasRivieccio, Umberto::virtual::5522::600Rivieccio, UmbertoRivieccio, UmbertoRivieccio, Umberto2024-05-212024-05-2120130022-3611 - eISSN 1573-0433https://doi.org/10.1007/s10992-011-9215-1https://hdl.handle.net/20.500.14468/19443A curious feature of Belnap’s “useful four-valued logic”, also known as first-degree entailment (FDE), is that the overdetermined value B (both true and false) is treated as a designated value. Although there are good theoretical reasons for this, it seems prima facie more plausible to have only one of the four values designated, namely T (exactly true). This paper follows this route and investigates the resulting logic, which we call Exactly True Logic.eninfo:eu-repo/semantics/openAccessjournal articleRelevant logicFirst degree entailmentBelnap’s four-valued logicDe Morgan latticesIn-and over complete data