In this paper the notions of α-migrative triangular norms over a fixed nullnorm and a fixed uninorm are introduced and studied. All solutions of the migrativity equation for all possible combinations of uninorms and nullnorms are analyzed and characterized. Similar study is done for triangular conorms.
154Emel Asici: On the α-migrativity of t-norms and t-conorms over nullnorms and uninorms Emel Asici: On the α-migrativity of t-norms and t-conorms over nullnorms and uninorms Now, we will introduce the definition of migrativity of a t-conorm S over a nullnorm F. Definition 7. Given a nullnorm F and α ∈]0, 1[, a t-conorm S is called α-migrative over F or (α, F)-migrative if S(F(α, x), y) = S(x, F(α, y)) f or all x, y ∈ [0, 1].(3)Since the extreme values of a correspond to the well known cases of t-norms and t-conorms, we will only deal with nullnorms with absorbing element a ∈]0, 1[. Lemma 2. Consider α ∈]0, 1[. Let S be a t-conorm, F be a nullnorm with absorbing element a. Then S is not α-migrative over F.It leads a contradiction that S is not α-migrative over F.It leads a contradiction that S is not α-migrative over F.Similarly to the case of nullnorms we want to study the migrativity of t-norms over uninorms.
Definition 8. Given a uninorm U and αSince the extreme values of e correspond to the well known cases of t-norms and t-conorms, we will only deal with uninorms with neutral element e ∈]0, 1[.
Lemma 3.Consider T be a t-norm and U be a uninorm with neutral element e. Then, T is e-migrative over U.Proof. T (U(e, x), y) = T (x, y) = T (x,U(e, y)) for all x, y ∈ [0, 1].Lemma 4. Consider α ∈]0, e[. Let T be a t-norm, U be a uninorm with neutral element e. Then T is not α-migrative over U.Proof. Since 0 < α, we have that U(0, 0) = 0 < U(α, 0). If T is α-migrative over U, then we haveLemma 5. Consider α ∈]e, 1[. Let T be a t-norm, U be a uninorm with neutral element e. Then T is not α-migrative over U. Proof. Since e < α, we have 1 = U(e, 1) < U(α, 1) c 2018 BISKA Bilisim Technology NTMSCI 6, No. 1, 153-158 (2018) / www.ntmsci.com 157by the monotonicity of U. So, it is obtained that U(α, 1) = 1. If T is α-migrative over U, then we have T (e,U(α, 1)) = T (e, 1) = e < α = T (α, 1) = T (U(α, e), 1) contradiction. So, T is not α-migrative over U.Definition 9. Given a uninorm U and α ∈]0, 1[, a t-conorm S is called α-migrative over U or (α,U)-migrative if S (U(α, x), y) = S(x,U(α, y)) f or all x, y ∈ [0, 1].Since the extreme values of e correspond to the well known cases of t-norms and t-conorms, we will only deal with uninorms with neutral element e ∈]0, 1[. Lemma 6. Consider S be a t-conorm and U be a uninorm with neutral element e. Then, S is e-migrative over U. Proof. S(U(e, x), y) = S(x, y) = S(x,U(e, y)) for all x, y ∈ [0, 1]. Lemma 7. Consider α ∈]0, e[. Let S be a t-conorm, U be a uninorm with neutral element e. Then S is not α-migrative over U. Proof. Since α < e, we have that U(α, 0) < U(e, 0) = 0 by the monotonicity of U. So, it is obtained that U(α, 0) = 0. If S is α-migrative over U, then we have S(U(α, e)...