| Firstly,we define an operation Nn based on the weak negation n on[0,1],and then prove that Nn is a weak negation in L(the set of normal and convex functions of M)but not in M.The properties of the operation Nn in M and the subalgebra L are discussed.And then,we proved that the operation Nn satisfies the De morgan's laws in M,when the weak negation n is involutive n(n(x))=x.Secondly,we point out some flaws about a algorithm in the paper(Harding J,Walker C,Walker E.Partial orders on fuzzy truth value algebras[J].Int.J.Uncertainty,Fuzziness and Knowledge-Based Systems,2015,23:193-219.).Finally,we modify these flaws and give a new algorithm to compute these covers in the lattice of convex normal functions of mn under the double order. |
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