A

  • Absolute value preserving On Preserving Properties of Linear Maps on $C^{*}$-algebras [Volume 17, Issue 1, 2020, Pages 125-137]

  • Akaike information criterion (AIC) Using Copulas to Model Dependence Between Crude Oil Prices of West Texas Intermediate and Brent-Europe [Volume 17, Issue 4, 2020, Pages 49-59]

  • Almost contraction Best Proximity Point Results for Almost Contraction and Application to Nonlinear Differential Equation [Volume 17, Issue 2, 2020, Pages 119-138]

  • Almost contraction mappings An Example of Data Dependence Result for The Class of Almost Contraction Mappings [Volume 17, Issue 1, 2020, Pages 139-155]

  • Almost convergence On the Spaces of $lambda _{r}$-almost Convergent and $lambda _{r}$-almost Bounded Sequences [Volume 17, Issue 3, 2020, Pages 117-130]

  • Ando's inequality Inequalities of Ando's Type for $n$-convex Functions [Volume 17, Issue 2, 2020, Pages 139-159]

  • Applications A New Iterative Algorithm for Multivalued Nonexpansive Mappping and Equlibruim Problems with Applications [Volume 17, Issue 2, 2020, Pages 1-22]

  • Automatically bounded and $w^*$-$w^*$-continuous $n$-factorization Property of Bilinear Mappings [Volume 17, Issue 3, 2020, Pages 161-173]

B

  • Banach algebra Joint and Generalized Spectral Radius of Upper Triangular Matrices with Entries in a Unital Banach Algebra [Volume 17, Issue 3, 2020, Pages 175-188]

  • Banach algebra Uniform Convergence to a Left Invariance on Weakly Compact Subsets [Volume 17, Issue 3, 2020, Pages 81-91]

  • Basic $A-$factor block circulant matrix Some Results on the Field of Values of Matrix Polynomials [Volume 17, Issue 2, 2020, Pages 55-68]

  • Basicity On the Basicity of Systems of Sines and Cosines with a Linear Phase in Morrey-Type Spaces [Volume 17, Issue 4, 2020, Pages 85-93]

  • Bazilevic function On Certain Generalized Bazilevic type Functions Associated with Conic Regions [Volume 17, Issue 4, 2020, Pages 13-23]

  • Besov spaces Integral Operators on the Besov Spaces and Subclasses of Univalent Functions [Volume 17, Issue 4, 2020, Pages 61-69]

  • Bilinear map $n$-factorization Property of Bilinear Mappings [Volume 17, Issue 3, 2020, Pages 161-173]

  • Bipolar metric space Caristi Type Cyclic Contraction and Coupled Fixed Point Results in Bipolar Metric Spaces [Volume 17, Issue 1, 2020, Pages 1-22]

  • Bornological completion Bornological Completion of Locally Convex Cones [Volume 17, Issue 2, 2020, Pages 173-183]

  • Bornological cones Bornological Completion of Locally Convex Cones [Volume 17, Issue 2, 2020, Pages 173-183]

  • Bornological convergence Bornological Completion of Locally Convex Cones [Volume 17, Issue 2, 2020, Pages 173-183]

  • Bounded boundary rotation On Certain Generalized Bazilevic type Functions Associated with Conic Regions [Volume 17, Issue 4, 2020, Pages 13-23]

C

  • CAT(0) metric space On the Monotone Mappings in CAT(0) Spaces [Volume 17, Issue 2, 2020, Pages 107-117]

  • Chaotic measure On Measure Chaotic Dynamical Systems [Volume 17, Issue 4, 2020, Pages 25-37]

  • Clifford semigroup First and Second Module Cohomology Groups for Non Commutative Semigroup Algebras [Volume 17, Issue 4, 2020, Pages 39-47]

  • Coefficient bound Some Properties of Certain Subclass of Meromorphic Functions Associated with $(p , q)$-derivative [Volume 17, Issue 4, 2020, Pages 71-84]

  • Cohomology group First and Second Module Cohomology Groups for Non Commutative Semigroup Algebras [Volume 17, Issue 4, 2020, Pages 39-47]

  • Common fixed point Caristi Type Cyclic Contraction and Coupled Fixed Point Results in Bipolar Metric Spaces [Volume 17, Issue 1, 2020, Pages 1-22]

  • Common fixed point theorem Common Fixed Point Results on Complex-Valued $S$-Metric Spaces [Volume 17, Issue 2, 2020, Pages 83-105]

  • Compact operator Weighted Composition Operators Between Extended Lipschitz Algebras on Compact Metric Spaces [Volume 17, Issue 3, 2020, Pages 33-70]

  • Compatible mappings Caristi Type Cyclic Contraction and Coupled Fixed Point Results in Bipolar Metric Spaces [Volume 17, Issue 1, 2020, Pages 1-22]

  • Complex valued $S$-metric space Common Fixed Point Results on Complex-Valued $S$-Metric Spaces [Volume 17, Issue 2, 2020, Pages 83-105]

  • Conic regions On Certain Generalized Bazilevic type Functions Associated with Conic Regions [Volume 17, Issue 4, 2020, Pages 13-23]

  • Continuous $g$-Bessel family On Sum and Stability of Continuous $G$-Frames [Volume 17, Issue 1, 2020, Pages 157-169]

  • Continuous $g$-frame On Sum and Stability of Continuous $G$-Frames [Volume 17, Issue 1, 2020, Pages 157-169]

  • Continuous frames Generalized Continuous Frames for Operators [Volume 17, Issue 2, 2020, Pages 185-201]

  • Continuous frames On Some Characterization of Generalized Representation Wave-Packet Frames Based on Some Dilation Group [Volume 17, Issue 3, 2020, Pages 93-106]

  • Convergence analysis An Example of Data Dependence Result for The Class of Almost Contraction Mappings [Volume 17, Issue 1, 2020, Pages 139-155]

  • Convex functions of complex order Integral Operators on the Besov Spaces and Subclasses of Univalent Functions [Volume 17, Issue 4, 2020, Pages 61-69]

  • Copulas Using Copulas to Model Dependence Between Crude Oil Prices of West Texas Intermediate and Brent-Europe [Volume 17, Issue 4, 2020, Pages 49-59]

  • Coupled coincidence fixed Point Some Fixed Point Theorems in Generalized Metric Spaces Endowed with Vector-valued Metrics and Application in Linear and Nonlinear Matrix Equations [Volume 17, Issue 2, 2020, Pages 37-53]

  • Coupled fixed point Caristi Type Cyclic Contraction and Coupled Fixed Point Results in Bipolar Metric Spaces [Volume 17, Issue 1, 2020, Pages 1-22]

  • Coupled fixed point Some Fixed Point Theorems in Generalized Metric Spaces Endowed with Vector-valued Metrics and Application in Linear and Nonlinear Matrix Equations [Volume 17, Issue 2, 2020, Pages 37-53]

D

  • Data dependence An Example of Data Dependence Result for The Class of Almost Contraction Mappings [Volume 17, Issue 1, 2020, Pages 139-155]

  • Demiclosed‎ Strong Convergence of the Iterations of Quasi $phi$-nonexpansive Mappings and its Applications in Banach Spaces [Volume 17, Issue 3, 2020, Pages 71-80]

  • Differentiation composition operators Estimates of Norm and Essential norm of Differences of Differentiation Composition Operators on Weighted Bloch Spaces [Volume 17, Issue 1, 2020, Pages 109-124]

  • Dilation groups On Some Characterization of Generalized Representation Wave-Packet Frames Based on Some Dilation Group [Volume 17, Issue 3, 2020, Pages 93-106]

  • Dual frames On Some Characterization of Generalized Representation Wave-Packet Frames Based on Some Dilation Group [Volume 17, Issue 3, 2020, Pages 93-106]

E

  • Edmundson-Lah-Ribariv c inequality Inequalities of Ando's Type for $n$-convex Functions [Volume 17, Issue 2, 2020, Pages 139-159]

  • Equilibrium problems A New Iterative Algorithm for Multivalued Nonexpansive Mappping and Equlibruim Problems with Applications [Volume 17, Issue 2, 2020, Pages 1-22]

  • Equivalent norm Non-Equivalent Norms on $C^b(K)$ [Volume 17, Issue 4, 2020, Pages 1-11]

  • Essential norm Estimates of Norm and Essential norm of Differences of Differentiation Composition Operators on Weighted Bloch Spaces [Volume 17, Issue 1, 2020, Pages 109-124]

  • Extended Lipschitz algebra Weighted Composition Operators Between Extended Lipschitz Algebras on Compact Metric Spaces [Volume 17, Issue 3, 2020, Pages 33-70]

  • Extreme Point Some Properties of Certain Subclass of Meromorphic Functions Associated with $(p , q)$-derivative [Volume 17, Issue 4, 2020, Pages 71-84]

F

  • Factorization property $n$-factorization Property of Bilinear Mappings [Volume 17, Issue 3, 2020, Pages 161-173]

  • Favard's inequality A Version of Favard's Inequality for the Sugeno Integral [Volume 17, Issue 1, 2020, Pages 23-37]

  • Fixed point Fixed Point Theorems on Complete Quasi Metric Spaces Via C-class and A-Class Functions [Volume 17, Issue 2, 2020, Pages 23-36]

  • Fixed point On the Monotone Mappings in CAT(0) Spaces [Volume 17, Issue 2, 2020, Pages 107-117]

  • Fixed point New Generalization of Darbo's Fixed Point Theorem via $lpha$-admissible Simulation Functions with Application [Volume 17, Issue 2, 2020, Pages 161-171]

  • Fixed point On Fixed Point Results for Hemicontractive-type Multi-valued Mapping, Finite Families of Split Equilibrium and Variational Inequality Problems [Volume 17, Issue 3, 2020, Pages 189-217]

  • Fixed point Almost Multi-Cubic Mappings and a Fixed Point Application [Volume 17, Issue 3, 2020, Pages 131-143]

  • Fixed point Fixed Point Results for Extensions of Orthogonal Contraction on Orthogonal Cone Metric Space [Volume 17, Issue 4, 2020, Pages 95-107]

  • Fixed points Some Fixed Point Theorems in Generalized Metric Spaces Endowed with Vector-valued Metrics and Application in Linear and Nonlinear Matrix Equations [Volume 17, Issue 2, 2020, Pages 37-53]

  • Fixed point theorem Common Fixed Point Results on Complex-Valued $S$-Metric Spaces [Volume 17, Issue 2, 2020, Pages 83-105]

  • Fixed point theory On $F$-Weak Contraction of Generalized Multivalued Integral Type Mappings with $lpha $-admissible [Volume 17, Issue 1, 2020, Pages 57-67]

  • Frames Generalized Continuous Frames for Operators [Volume 17, Issue 2, 2020, Pages 185-201]

  • Frequently hypercyclic operators About Subspace-Frequently Hypercyclic Operators [Volume 17, Issue 3, 2020, Pages 107-116]

  • Fusion frame Continuous $k$-Fusion Frames in Hilbert Spaces [Volume 17, Issue 1, 2020, Pages 39-55]

  • Fuzzy integral inequality A Version of Favard's Inequality for the Sugeno Integral [Volume 17, Issue 1, 2020, Pages 23-37]

  • Fuzzy measure A Version of Favard's Inequality for the Sugeno Integral [Volume 17, Issue 1, 2020, Pages 23-37]

G

  • Generalized metric Some Fixed Point Theorems in Generalized Metric Spaces Endowed with Vector-valued Metrics and Application in Linear and Nonlinear Matrix Equations [Volume 17, Issue 2, 2020, Pages 37-53]

  • Generalized Spectral Radius Joint and Generalized Spectral Radius of Upper Triangular Matrices with Entries in a Unital Banach Algebra [Volume 17, Issue 3, 2020, Pages 175-188]

  • Geometric Joint Spectral Radius Joint and Generalized Spectral Radius of Upper Triangular Matrices with Entries in a Unital Banach Algebra [Volume 17, Issue 3, 2020, Pages 175-188]

  • Goodness of fit test (GOF) Using Copulas to Model Dependence Between Crude Oil Prices of West Texas Intermediate and Brent-Europe [Volume 17, Issue 4, 2020, Pages 49-59]

H

  • Hadamard product Some Properties of Certain Subclass of Meromorphic Functions Associated with $(p , q)$-derivative [Volume 17, Issue 4, 2020, Pages 71-84]

  • Hankel determinant On Certain Generalized Bazilevic type Functions Associated with Conic Regions [Volume 17, Issue 4, 2020, Pages 13-23]

  • Hilbert space A Common Fixed Point Theorem Using an Iterative Method [Volume 17, Issue 1, 2020, Pages 91-98]

  • Hyers-Ulam-Rassias stability On Approximate Solutions of the Generalized Radical Cubic Functional Equation in Quasi-$eta$-Banach Spaces [Volume 17, Issue 1, 2020, Pages 69-90]

  • Hyers-Ulam stability Almost Multi-Cubic Mappings and a Fixed Point Application [Volume 17, Issue 3, 2020, Pages 131-143]

  • Hypercyclic operators About Subspace-Frequently Hypercyclic Operators [Volume 17, Issue 3, 2020, Pages 107-116]

I

  • Integral operators Integral Operators on the Besov Spaces and Subclasses of Univalent Functions [Volume 17, Issue 4, 2020, Pages 61-69]

  • Inward condition A Common Fixed Point Theorem Using an Iterative Method [Volume 17, Issue 1, 2020, Pages 91-98]

  • Iteration Methods An Example of Data Dependence Result for The Class of Almost Contraction Mappings [Volume 17, Issue 1, 2020, Pages 139-155]

  • Iterative methods A New Iterative Algorithm for Multivalued Nonexpansive Mappping and Equlibruim Problems with Applications [Volume 17, Issue 2, 2020, Pages 1-22]

J

  • Joint Spectral Radius Joint and Generalized Spectral Radius of Upper Triangular Matrices with Entries in a Unital Banach Algebra [Volume 17, Issue 3, 2020, Pages 175-188]

K

  • K-frames Generalized Continuous Frames for Operators [Volume 17, Issue 2, 2020, Pages 185-201]

  • Krasnoselskii-Mann iterative method A Common Fixed Point Theorem Using an Iterative Method [Volume 17, Issue 1, 2020, Pages 91-98]

L

  • Limiting subdifferential Vector Optimization Problems and Generalized Vector Variational-Like Inequalities [Volume 17, Issue 2, 2020, Pages 69-82]

  • Linear convex combination Using Copulas to Model Dependence Between Crude Oil Prices of West Texas Intermediate and Brent-Europe [Volume 17, Issue 4, 2020, Pages 49-59]

  • Lipschitz mapping Weighted Composition Operators Between Extended Lipschitz Algebras on Compact Metric Spaces [Volume 17, Issue 3, 2020, Pages 33-70]

  • Locally convex cones Bornological Completion of Locally Convex Cones [Volume 17, Issue 2, 2020, Pages 173-183]

M

  • Matrix domain On the Spaces of $lambda _{r}$-almost Convergent and $lambda _{r}$-almost Bounded Sequences [Volume 17, Issue 3, 2020, Pages 117-130]

  • Matrix polynomial Some Results on the Field of Values of Matrix Polynomials [Volume 17, Issue 2, 2020, Pages 55-68]

  • Matrix transformations On the Spaces of $lambda _{r}$-almost Convergent and $lambda _{r}$-almost Bounded Sequences [Volume 17, Issue 3, 2020, Pages 117-130]

  • Measure of non-compactness New Generalization of Darbo's Fixed Point Theorem via $lpha$-admissible Simulation Functions with Application [Volume 17, Issue 2, 2020, Pages 161-171]

  • Meromorphic function Some Properties of Certain Subclass of Meromorphic Functions Associated with $(p , q)$-derivative [Volume 17, Issue 4, 2020, Pages 71-84]

  • Module cohomology group First and Second Module Cohomology Groups for Non Commutative Semigroup Algebras [Volume 17, Issue 4, 2020, Pages 39-47]

  • Monotone mapping On the Monotone Mappings in CAT(0) Spaces [Volume 17, Issue 2, 2020, Pages 107-117]

  • Monotone mapping On Fixed Point Results for Hemicontractive-type Multi-valued Mapping, Finite Families of Split Equilibrium and Variational Inequality Problems [Volume 17, Issue 3, 2020, Pages 189-217]

  • Morrey space On the Basicity of Systems of Sines and Cosines with a Linear Phase in Morrey-Type Spaces [Volume 17, Issue 4, 2020, Pages 85-93]

  • Multi-cubic mapping Almost Multi-Cubic Mappings and a Fixed Point Application [Volume 17, Issue 3, 2020, Pages 131-143]

  • Multivalued integral operators On $F$-Weak Contraction of Generalized Multivalued Integral Type Mappings with $lpha $-admissible [Volume 17, Issue 1, 2020, Pages 57-67]

  • Multivalued mappings A New Iterative Algorithm for Multivalued Nonexpansive Mappping and Equlibruim Problems with Applications [Volume 17, Issue 2, 2020, Pages 1-22]

N

  • Nonexpansive mapping A Common Fixed Point Theorem Using an Iterative Method [Volume 17, Issue 1, 2020, Pages 91-98]

  • Nonexpansive mapping On the Monotone Mappings in CAT(0) Spaces [Volume 17, Issue 2, 2020, Pages 107-117]

  • Nonsmooth functions Vector Optimization Problems and Generalized Vector Variational-Like Inequalities [Volume 17, Issue 2, 2020, Pages 69-82]

  • Normed vector space Non-Equivalent Norms on $C^b(K)$ [Volume 17, Issue 4, 2020, Pages 1-11]

O

  • Offline handwritten signature Use of the Shearlet Transform and Transfer Learning in Offline Handwritten Signature Verification and Recognition [Volume 17, Issue 3, 2020, Pages 1-31]

  • Operator means Inequalities of Ando's Type for $n$-convex Functions [Volume 17, Issue 2, 2020, Pages 139-159]

  • Optimization About One Sweep Algorithm for Solving Linear-Quadratic Optimization Problem with Unseparated Two-Point Boundary Conditions [Volume 17, Issue 1, 2020, Pages 99-107]

  • Orthogonal cone metric Fixed Point Results for Extensions of Orthogonal Contraction on Orthogonal Cone Metric Space [Volume 17, Issue 4, 2020, Pages 95-107]

  • Orthogonal contraction Fixed Point Results for Extensions of Orthogonal Contraction on Orthogonal Cone Metric Space [Volume 17, Issue 4, 2020, Pages 95-107]

  • Orthogonal set Fixed Point Results for Extensions of Orthogonal Contraction on Orthogonal Cone Metric Space [Volume 17, Issue 4, 2020, Pages 95-107]

P

  • Parameter estimation Using Copulas to Model Dependence Between Crude Oil Prices of West Texas Intermediate and Brent-Europe [Volume 17, Issue 4, 2020, Pages 49-59]

  • Parseval continuous $g$-frame On Sum and Stability of Continuous $G$-Frames [Volume 17, Issue 1, 2020, Pages 157-169]

  • Partial sum Some Properties of Certain Subclass of Meromorphic Functions Associated with $(p , q)$-derivative [Volume 17, Issue 4, 2020, Pages 71-84]

  • Periodic point Fixed Point Results for Extensions of Orthogonal Contraction on Orthogonal Cone Metric Space [Volume 17, Issue 4, 2020, Pages 95-107]

  • Perturbation Some Results on the Field of Values of Matrix Polynomials [Volume 17, Issue 2, 2020, Pages 55-68]

  • Pseudoinvex functions Vector Optimization Problems and Generalized Vector Variational-Like Inequalities [Volume 17, Issue 2, 2020, Pages 69-82]

Q

  • Q-duality Continuous $k$-Fusion Frames in Hilbert Spaces [Volume 17, Issue 1, 2020, Pages 39-55]

  • Quasi metric space Fixed Point Theorems on Complete Quasi Metric Spaces Via C-class and A-Class Functions [Volume 17, Issue 2, 2020, Pages 23-36]

R

  • Representation frames On Some Characterization of Generalized Representation Wave-Packet Frames Based on Some Dilation Group [Volume 17, Issue 3, 2020, Pages 93-106]

  • Resolvent Strong Convergence of the Iterations of Quasi $phi$-nonexpansive Mappings and its Applications in Banach Spaces [Volume 17, Issue 3, 2020, Pages 71-80]

  • Riccati equations About One Sweep Algorithm for Solving Linear-Quadratic Optimization Problem with Unseparated Two-Point Boundary Conditions [Volume 17, Issue 1, 2020, Pages 99-107]

S

  • Schwarzian norm Integral Operators on the Besov Spaces and Subclasses of Univalent Functions [Volume 17, Issue 4, 2020, Pages 61-69]

  • Sensitivity On Measure Chaotic Dynamical Systems [Volume 17, Issue 4, 2020, Pages 25-37]

  • Shearlet transform Use of the Shearlet Transform and Transfer Learning in Offline Handwritten Signature Verification and Recognition [Volume 17, Issue 3, 2020, Pages 1-31]

  • Signature recognition Use of the Shearlet Transform and Transfer Learning in Offline Handwritten Signature Verification and Recognition [Volume 17, Issue 3, 2020, Pages 1-31]

  • Signature verification Use of the Shearlet Transform and Transfer Learning in Offline Handwritten Signature Verification and Recognition [Volume 17, Issue 3, 2020, Pages 1-31]

  • Simulation functions New Generalization of Darbo's Fixed Point Theorem via $lpha$-admissible Simulation Functions with Application [Volume 17, Issue 2, 2020, Pages 161-171]

  • Solidarities Inequalities of Ando's Type for $n$-convex Functions [Volume 17, Issue 2, 2020, Pages 139-159]

  • Starlike functions of complex order Integral Operators on the Besov Spaces and Subclasses of Univalent Functions [Volume 17, Issue 4, 2020, Pages 61-69]

  • Strongly Arens irregular $n$-factorization Property of Bilinear Mappings [Volume 17, Issue 3, 2020, Pages 161-173]

  • Strongly zero-product preserving map Non-Equivalent Norms on $C^b(K)$ [Volume 17, Issue 4, 2020, Pages 1-11]

  • Subspace-frequently hypercyclic operators About Subspace-Frequently Hypercyclic Operators [Volume 17, Issue 3, 2020, Pages 107-116]

  • Subspace-hypercyclic operators About Subspace-Frequently Hypercyclic Operators [Volume 17, Issue 3, 2020, Pages 107-116]

  • Sugeno integral A Version of Favard's Inequality for the Sugeno Integral [Volume 17, Issue 1, 2020, Pages 23-37]

  • Supercontactive mapping Weighted Composition Operators Between Extended Lipschitz Algebras on Compact Metric Spaces [Volume 17, Issue 3, 2020, Pages 33-70]

  • Sweep Algorithm About One Sweep Algorithm for Solving Linear-Quadratic Optimization Problem with Unseparated Two-Point Boundary Conditions [Volume 17, Issue 1, 2020, Pages 99-107]

  • System of cosines On the Basicity of Systems of Sines and Cosines with a Linear Phase in Morrey-Type Spaces [Volume 17, Issue 4, 2020, Pages 85-93]

  • System of sines On the Basicity of Systems of Sines and Cosines with a Linear Phase in Morrey-Type Spaces [Volume 17, Issue 4, 2020, Pages 85-93]

T

  • Transfer learning Use of the Shearlet Transform and Transfer Learning in Offline Handwritten Signature Verification and Recognition [Volume 17, Issue 3, 2020, Pages 1-31]

U

  • Unitary preserving On Preserving Properties of Linear Maps on $C^{*}$-algebras [Volume 17, Issue 1, 2020, Pages 125-137]

  • Univalent functions On Certain Generalized Bazilevic type Functions Associated with Conic Regions [Volume 17, Issue 4, 2020, Pages 13-23]

  • Upper Triangular Matrix Joint and Generalized Spectral Radius of Upper Triangular Matrices with Entries in a Unital Banach Algebra [Volume 17, Issue 3, 2020, Pages 175-188]

V

W

  • Weak$^*$ topology Uniform Convergence to a Left Invariance on Weakly Compact Subsets [Volume 17, Issue 3, 2020, Pages 81-91]

  • Weak almost periodic Uniform Convergence to a Left Invariance on Weakly Compact Subsets [Volume 17, Issue 3, 2020, Pages 81-91]

  • Weak amenability First and Second Module Cohomology Groups for Non Commutative Semigroup Algebras [Volume 17, Issue 4, 2020, Pages 39-47]

  • Weak module amenability First and Second Module Cohomology Groups for Non Commutative Semigroup Algebras [Volume 17, Issue 4, 2020, Pages 39-47]

  • Weighted Bloch spaces Estimates of Norm and Essential norm of Differences of Differentiation Composition Operators on Weighted Bloch Spaces [Volume 17, Issue 1, 2020, Pages 109-124]

  • Weighted composition operator Weighted Composition Operators Between Extended Lipschitz Algebras on Compact Metric Spaces [Volume 17, Issue 3, 2020, Pages 33-70]

Z