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Interval-valued Intuitionistic Fuzzy Rough Sets - Rough Set Theory ...

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Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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<strong>Interval</strong>-<strong>valued</strong> intuitionistic<br />

fuzzy-rough sets<br />

Yanhua Wu, Kedian Li<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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Department of Mathematics and Information<br />

Science, Zhangzhou Normal University, Zhangzhou<br />

363000, P. R. China<br />

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<strong>Interval</strong>-<strong>valued</strong> intuitionistic fuzzy-rough<br />

sets<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> <strong>Intuitionistic</strong> <strong>Fuzzy</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> <strong>Intuitionistic</strong> <strong>Fuzzy</strong>-<strong>Rough</strong> <strong><strong>Set</strong>s</strong> Model<br />

<strong>Interval</strong>-<strong>valued</strong> <strong>Intuitionistic</strong> <strong>Fuzzy</strong> <strong><strong>Set</strong>s</strong> and Hamming Distance<br />

Approximation <strong>Rough</strong>ness<br />

References<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

1 Introduction<br />

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The present paper is inspired by the ideology of [16]. This paper combines<br />

interval-<strong>valued</strong> intuitionistic fuzzy sets and rough sets. It studies rougheness in<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

interval-<strong>valued</strong> intuitionistic fuzzy sets and proposes one kind of interval-<strong>valued</strong><br />

intuitionistic fuzzy-rough sets models under the equivalence relation in crisp<br />

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sets. That extends the classical rough set defined by Pawlak. All the properties<br />

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are established over finite fields in this paper.<br />

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Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

2 <strong>Interval</strong>-<strong>valued</strong> <strong>Intuitionistic</strong> <strong>Fuzzy</strong> <strong><strong>Set</strong>s</strong><br />

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Definition 1.[2] Let a set X = {x 1 , x 2 , · · · , x n } be fixed. An interval<strong>valued</strong><br />

intuitionistic fuzzy set A in X is an object having the form<br />

A = {〈x, µ A (x), ν A (x)〉|x ∈ X}<br />

where µ A (x) ⊂ [0, 1] and ν A (x) ⊂ [0, 1] satisfy<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

supµ A (x) + supν A (x) ≤ 1<br />

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for all x ∈ X, and µ A (x) and ν A (x) are, respectively, called the degree<br />

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of membership and the degree of non-membership of the element x ∈<br />

X to A. If supµ A (x)=infµ A (x) and supν A (x)=infν A (x), then A will<br />

degenerate to be a standard intuitionistic fuzzy set.<br />

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Definition 2.[2] Let<br />

A = {〈x, µ A (x), ν A (x)〉|x ∈ X},<br />

A 1 = {〈x, µ A1 (x), ν A1 (x)〉|x ∈ X},<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

A 2 = {〈x, µ A2 (x), ν A2 (x)〉|x ∈ X}<br />

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be interval-<strong>valued</strong> intuitionistic fuzzy sets. Denote,<br />

µ LA1 ,A 2<br />

(x) = {inf µ A1 (x), inf µ A2 (x)}, µ UA1 ,A 2<br />

(x) = {sup µ A1 (x), sup µ A2 (x)};<br />

ν LA1 ,A 2<br />

(x) = {inf ν A1 (x), inf ν A2 (x)}, ν UA1 ,A 2<br />

(x) = {sup ν A1 (x), sup ν A2 (x)},<br />

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then<br />

⋃<br />

A 1 A2 = {〈x, [max µ LA1 ,A 2<br />

(x), max µ UA1 ,A 2<br />

(x)],<br />

[min ν LA1 ,A 2<br />

(x), min ν UA1 ,A 2<br />

(x)]〉|x ∈ X};<br />

⋂<br />

A 1 A2 = {〈x, [min µ LA1 ,A 2<br />

(x), min µ UA1 ,A 2<br />

(x)],<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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[max ν LA1 ,A 2<br />

(x), max ν UA1 ,A 2<br />

(x)]〉|x ∈ X};<br />

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A c = {〈x, ν A (x), µ A (x)〉|x ∈ X}.<br />

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Definition 3.[9] Let F L (x) be the set of all interval-<strong>valued</strong> intuitionistic<br />

fuzzy sets of X, then<br />

A 1 ⊆ A 2 ,<br />

we have<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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inf µ A1 (x) ≤ inf µ A2 (x), sup µ A1 (x) ≤ sup µ A2 (x);<br />

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inf ν A1 (x) ≥ inf ν A2 (x), sup ν A1 (x) ≥ sup ν A2 (x).<br />

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Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

3 <strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

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Definition 4. [8] Let U be a set called the universe and R an equivalence<br />

relation of U, we call (U, R) a Pawlak approximation space. Any<br />

subset X ⊆ U, can be characterized with respect to the relation R .<br />

The equivalence class of element x by the relation R will be denoted<br />

by [x] R , that is, [x i ] R = {x j |(x i , x j ) ∈ R}.<br />

For all X ⊆ U,the subsets R(X) = {x i |[x i ] R ⊆ X}, R(X) =<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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{x i |[x i ] R<br />

⋂ X ≠ ∅}, are called the R-lower approximations of Xand<br />

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the R-upper approximations of X respectively. If R(X) = R(X), we<br />

say that X is definable. Any pair of the form R(X) = (R(X), R(X))<br />

is called a rough set of is called a rough set of X.<br />

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Theorem 1. [14] Let (U, R) be a approximation space, For all X ⊆<br />

U,denote<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

R ′ (X) = ⋃ {[x i ] R |[x i ] R ⊆ X},<br />

R ′ (X) = ⋃ {[x i ] R |[x i ] R<br />

⋂ X ≠ ∅},<br />

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then<br />

R ′ (X) = R(X), R ′ (X) = R(X).<br />

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Theorem 2. [14] Let (U, R) be an approximation space. For X ⊆ U,<br />

R(X) and R(X) are the R-lower and R-upper approximations of X,<br />

respectively. Then we have<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

(1) R(U) = R(U) = U, R(∅) = R(∅) = ∅;<br />

(2) R(X) ⊆ X ⊆ R(X);<br />

(3) R(X ⋂ Y ) = R(X) ⋂ R(Y ), R(X ⋃ Y ) = R(X) ⋃ R(Y );<br />

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(4) R(X C ) = (R(X)) C , R(X C ) = (R(X)) C .<br />

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4 <strong>Interval</strong>-<strong>valued</strong> <strong>Intuitionistic</strong> <strong>Fuzzy</strong>-<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong> Model<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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Definition 5.[16] Let (U, R) be a Pawlak approximation space, for<br />

fuzzy set A on U . Denote<br />

R(A)(x) = min{A(y)|y ∈ [x] R },<br />

R(A)(x) = max{A(y)|y ∈ [x] R }.<br />

Then R(A) and R(A) are called the lower and upper approximations<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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of fuzzy sets A with respect to approximation space (U, R), respectively.<br />

We call (R(A), R(A)) the rough fuzzy set of A with respect to<br />

(U, R).<br />

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Definition 6. Let (U, R) be a Pawlak approximation space, for an<br />

interval-<strong>valued</strong> intuitionistic fuzzy set A = {〈x, µ A (x), ν A (x)〉|x ∈ X}<br />

denote,<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

A R = {〈x, [ inf<br />

y∈[x] R<br />

{inf µ A (y)}, inf<br />

y∈[x] R<br />

{sup µ A (y)}],<br />

[ sup<br />

y∈[x] R<br />

{inf ν A (y)}, sup<br />

y∈[x] R<br />

{sup ν A (y)}]〉|x ∈ U},<br />

A R = {〈x, [ sup<br />

y∈[x] R<br />

{inf µ A (y)}, sup<br />

y∈[x] R<br />

{sup µ A (y)}],<br />

[ inf<br />

y∈[x] R<br />

{inf ν A (y)}, inf<br />

y∈[x] R<br />

{sup ν A (y)}]〉|x ∈ U},<br />

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and<br />

It is easy to see that<br />

[ inf<br />

y∈[x] R<br />

{inf µ A (y)}, inf<br />

y∈[x] R<br />

{sup µ A (y)}] ⊂ [0, 1],<br />

[ sup<br />

y∈[x] R<br />

{inf ν A (y)}, sup<br />

y∈[x] R<br />

{sup ν A (y)}] ⊂ [0, 1],<br />

inf {sup µ A (y)} + sup {sup ν A (y)} ≤ 1,<br />

y∈[x] R y∈[x] R<br />

then A R is an interval-<strong>valued</strong> intuitionistic fuzzy set.<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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and<br />

Similarly, we have<br />

[ sup<br />

y∈[x] R<br />

{inf µ A (y)}, sup<br />

y∈[x] R<br />

{sup µ A (y)}] ⊂ [0, 1],<br />

[ inf<br />

y∈[x] R<br />

{inf ν A (y)}, inf<br />

y∈[x] R<br />

{sup ν A (y)}] ⊂ [0, 1],<br />

sup {sup µ A (y)} + inf {sup ν A (y)} ≤ 1,<br />

y∈[x] R<br />

y∈[x] R<br />

then A R is also an interval-<strong>valued</strong> intuitionistic fuzzy set.<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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If A R = A R , then A is a definable set, otherwise A is an interval<strong>valued</strong><br />

intuitionistic fuzzy rough set. A R and A R are called the lower<br />

and upper approximations of interval-<strong>valued</strong> intuitionistic fuzzy set<br />

with respect to approximation space , respectively. and are simply denoted<br />

by A with respect to approximation space (U, R), respectively.<br />

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A R and A R are simply denoted by A and A hereafter.<br />

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Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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Theorem 3. Let A, B be interval-<strong>valued</strong> intuitionistic fuzzy sets and<br />

A and A the lower and upper approximations of interval-<strong>valued</strong> intuitionistic<br />

fuzzy set A with respect to approximation space (U, R), respectively.<br />

B and B be the lower and upper approximations of interval<strong>valued</strong><br />

intuitionistic fuzzy set Bwith respect to approximation space<br />

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(U, R), respectively. Then we have<br />

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(1) A ⊆ A ⊆ A;<br />

(2) A ⋃ B = A ⋃ B, A ⋂ B = A ⋂ B;<br />

(3) A ⋃ B ⊆ A ⋃ B, A ⋂ B ⊆ A ⋂ B;<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

(4) (A) = (A) = A, (A) = (A) = A;<br />

(5) U = U, ∅ = ∅;<br />

(6) If A ⊆ B, then A ⊆ B and A ⊆ B;<br />

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(7) A C = (A) C , A C = (A) C .<br />

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Remark 1. “ sup ” is equal to “ max ”§“ inf ” is equal to “ min ” over<br />

finite fields.<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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Definition 7. Let (U, R) be a Pawlak approximation space, and A and<br />

B two interval-<strong>valued</strong> intuitionistic fuzzy sets over U .<br />

If A = B, then A and B are called interval-<strong>valued</strong> intuitionistic fuzzy<br />

lower rough equal.<br />

If A = B, then A and B are called interval-<strong>valued</strong> intuitionistic fuzzy<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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upper rough equal.<br />

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If A = B,A = B, then A and B are called interval-<strong>valued</strong> intuitionistic<br />

fuzzy rough equal.<br />

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Theorem 4. Let (U, R) be a Pawlak approximation space, and A and<br />

B two interval-<strong>valued</strong> intuitionistic fuzzy sets over U. Then,<br />

(1) A = B ⇔ A ⋂ B = A, A ⋂ B = B;<br />

(2) A = B ⇔ A ⋃ B = A, A ⋃ B = B;<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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(3) If A = A ′ and B = B ′ , then A ⋃ B = A ′ ⋃ B ′ ;<br />

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◮<br />

(4) If A = A ′ and B = B ′ , then A ⋂ B = A ′ ⋂ B<br />

′;<br />

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(5) If A ⊆ B and B = ∅, then A = ∅;<br />

(6) If A ⊆ B and B = U, then A = U;<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

(7) If A = ∅ or B = ∅, then A ⋂ B = ∅;<br />

(8) If A = U or B = U, then A ⋃ B = U;<br />

(9) A = U ⇔ A = U;(10)A = ∅ ⇔ A = ∅;<br />

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5 <strong>Interval</strong>-<strong>valued</strong> <strong>Intuitionistic</strong> <strong>Fuzzy</strong> <strong><strong>Set</strong>s</strong><br />

and Hamming Distance<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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Definition 8. [12] LetA 1 and A 2 be interval-<strong>valued</strong> intuitionistic fuzzy<br />

sets over U then the standard hamming distance of A 1 and A 2 is defined<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

as follows<br />

d(A 1 , A 2 ) = 1<br />

4n<br />

n∑<br />

(|µ L A 1<br />

(x j ) − µ L A 2<br />

(x j )| + |µ U A 1<br />

(x j ) − µ U A 2<br />

(x j )|<br />

j=1<br />

+|ν L A 1<br />

(x j ) − ν L A 2<br />

(x j )| + |ν U A 1<br />

(x j ) − ν U A 2<br />

(x j )|)<br />

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And we can obtain the standard hamming distance of A and A from<br />

Definition 8,<br />

d(A, A) = 1<br />

4n<br />

n∑<br />

(|µ L A (x j) − µ L(x A j)| + |µ U A (x j) − µ U(x A j)|<br />

j=1<br />

+|ν L A (x j) − ν L A (x j)| + |ν U A (x j) − ν U A (x j)|)<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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where<br />

µ L A (x j) = inf<br />

y∈[x] R<br />

{inf µ A (y)},µ U A (x j) = inf<br />

y∈[x] R<br />

{sup µ A (y)},<br />

ν L A (x j) = sup<br />

y∈[x] R<br />

{inf ν A (y)},ν U A (x j) = sup<br />

y∈[x] R<br />

{sup ν A (y)},<br />

µ L A (x j) = sup<br />

y∈[x] R<br />

{inf µ A (y)},µ U A (x j) = sup<br />

y∈[x] R<br />

{sup µ A (y)},<br />

ν L A (x j) = inf<br />

y∈[x] R<br />

{inf ν A (y)},ν U A (x j) = inf<br />

y∈[x] R<br />

{sup ν A (y)},<br />

y = x j , (j = 1, 2 · · · n).<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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Theorem 5. Let (U, R) be approximation space, A be an interval<strong>valued</strong><br />

intuitionistic fuzzy set over U . Then<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

(1) If d(A, A) = 0, then A is a definable set.<br />

(2) If 0 < d(A, A) < 1,then A is an interval-<strong>valued</strong> intuitionistic<br />

fuzzy rough set.<br />

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Theorem 6. Let (U, R) be a Pawlak approximation space, and A and<br />

B two interval-<strong>valued</strong> intuitionistic fuzzy sets over U. Then<br />

(1) d(A, A) ≥ d(A, A) and d(A, A) ≥ d(A, A);<br />

(2) d(A ⋃ B, A ⋃ B) = 0, d(A ⋂ B, A ⋂ B) = 0;<br />

(3) d(A ⋃ B, A ⋃ B) ≥ d(A ⋃ B, A ⋃ B)<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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and<br />

d(A ⋃ B, A ⋃ B) ≥ d(A ⋃ B, A ⋃ B);<br />

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◮<br />

and d(A ⋂ B, A ⋂ B) ≥ d(A ⋂ B, A ⋂ B)<br />

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d(A ⋂ B, A ⋂ B) ≥ d(A ⋂ B, A ⋂ B);<br />

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(4) d((A), (A)) = 0, d((A), A) = 0, d((A), A) = 0;<br />

d((A), (A)) = 0, d((A), A) = 0, d((A), A) = 0;<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

(5) d(U, U) = 0, d(∅, ∅) = 0<br />

(6) If A ⊆ B, then d(A, B) ≥ d(A, B) and d(A, B) ≥ d(B, B);<br />

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d(A, B) ≥ d(A, A) and d(A, B) ≥ d(A, B);<br />

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(7) d(A C , (A) C ) = 0, d(A C , (A) C ) = 0;<br />

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Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

6 Approximation <strong>Rough</strong>ness<br />

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Definition 9. Let F L (X) be the set of all interval-<strong>valued</strong> intuitionistic<br />

fuzzy sets of X. For A ∈ F L (X), x ∈ X, X ⊆ U, U a nonempty<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

universe, R an equivalence relation on U, [x] R the equivalence class of<br />

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element x by the relation R, then its cardinality |A| is defined as follows<br />

|A| = sup(( ⋃ µ A (y)) ⋃ ( ⋃ ν A (y)))−inf(( ⋃ µ A (y)) ⋃ ( ⋃ ν A (y))).<br />

y∈[x] R y∈[x] R y∈[x] R y∈[x] R<br />

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Definition 10. Let (U, R) be a Pawlak approximation space, and A<br />

an interval-<strong>valued</strong> intuitionistic fuzzy set over U . The approximation<br />

roughness ρ R (A) of A with respect to approximation space (U, R) is<br />

defined by ρ R (A) = 1 − |A|<br />

|A| . If |A| = 0, we have ρ R(A) = 0 . The approximation<br />

precision η R (A) of A with respect to approximation space<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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(U, R) is defined by η R (A) = |A|<br />

|A| .<br />

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◮<br />

It is clear that 0 ≤ ρ R (A) ≤ 1, 0 ≤ η R (A) ≤ 1.<br />

If A is a definable set, we have ρ R (A) = 0, η R (A) = 1.<br />

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Theorem 7. Let (U, R) be a Pawlak approximation space, and Aan<br />

interval-<strong>valued</strong> intuitionistic fuzzy set over U.<br />

(1) If d(A, A) = 0, then ρ R (A) = 0, η R (A) = 1.<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

(2) If 0 < d(A, A) < 1, then 0 < ρ R (A) < 1, 0 < η R (A) < 1.<br />

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Theorem 8.<br />

Let (U, R) be a Pawlak approximation space, A an<br />

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interval-<strong>valued</strong> intuitionistic fuzzy set over U, S an equivalence relation<br />

on U , and S ⊆ R , then A R ⊆ A S , A S ⊆ A R .<br />

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Theorem 9. Let S ⊆ R and A be an interval-<strong>valued</strong> intuitionistic<br />

fuzzy set over U . Then<br />

(1) η S (A) ≥ η R (A);<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

(2) ρ S (A) ≤ ρ R (A).<br />

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Remark 2. We can obtain from Theorem 9 that the more fineness partition<br />

is, the more approximation precision is, the less approximation<br />

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7 References<br />

[1] ATANASSOV K. <strong>Intuitionistic</strong> fuzzy sets [J]. <strong>Fuzzy</strong> <strong><strong>Set</strong>s</strong> and Systems,<br />

1986, 20(1): 87-96.<br />

[2] ATANASSOV K, GARGOV G. <strong>Interval</strong>-<strong>valued</strong> intuitionistic fuzzy<br />

sets [J]. <strong>Fuzzy</strong> <strong><strong>Set</strong>s</strong> and Systems, 1989, 31: 343-249.<br />

[3] BUSTINCE H, BURILLO P. Vague sets are intuitionistic fuzzy sets<br />

[J]. <strong>Fuzzy</strong> <strong><strong>Set</strong>s</strong> and Systems, 1996, 79(3): 403-405.<br />

[4] CORNELIS C, COCK M D, KERRE E E. <strong>Intuitionistic</strong> fuzzy rough<br />

sets: at the crossroads of imperfect knowledge [J]. Expert Systems,<br />

2003, 20(5): 260õ270.<br />

[5] DUBOIS D, PRADE H. <strong>Rough</strong> fuzzy sets and fuzzy rough sets [J].<br />

International Journal of General Systems, 1990, 17(2): 191õ209.<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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[6] GAU W L, BUEHRER D J. Vague sets [J]. IEEE Trans on Systems,<br />

Man, and Cybernetics, 1993, 23(2): 610-614.<br />

[7] GONG Z T, SUN B Z, CHEN D G.. <strong>Rough</strong> set theory for interval<strong>valued</strong><br />

fuzzy information systems [J], Information Sciences, 2008,<br />

178(8): 1968õ1985.<br />

[8] PAWLAK Z. <strong>Rough</strong> sets [J]. International Journal of Computer and<br />

Information Sciences, 1982, 11: 341-356.<br />

[9] TAPAS K M, SAMANTA S K. Topology of interval-<strong>valued</strong> intuitionistic<br />

fuzzy sets [J]. <strong>Fuzzy</strong> <strong><strong>Set</strong>s</strong> and Systems, 2001, 119(3): 483-<br />

494.<br />

[10] WU W-Z, MI J-S, ZHANG W-X. Generalized fuzzy rough sets<br />

[J]. Information Sciences, 2003, 151: 263õ282.<br />

[11] WU W-Z, ZHANG W-X. Constructive and axiomatic approaches<br />

of fuzzy approximation operators [J. Information Sciences, 2004, 159:<br />

233õ254.<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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[12] XU Z-S. The <strong>Theory</strong> and Application of <strong>Intuitionistic</strong> <strong>Fuzzy</strong> Information<br />

Integration [M]. Beijing: Science Press, 2008: 45-46, 89-93.<br />

[13] ZHANG Z-M. An interval-<strong>valued</strong> intuitionistic fuzzy rough set<br />

model [J]. Fundamenta Information, 2009, 97: 471õ498.<br />

[14] ZHANG W-X, QIU G.-F. Uncertain Decision Making Based on<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong> [M]. Beijing: Tsinghua University Press, 2005: 14-16.<br />

[15] ZHUO L, WU W-Z, ZHANG W-X. On intuitionistic fuzzy rough<br />

sets and their topological structures [J]. International Journal of General<br />

Systems, 2009, 38: 589õ616.<br />

[16] ZHANG Z-L, ZHANG J-L, XIAO Q-M. <strong>Fuzzy</strong> algebra and rough<br />

algebra [M]. Wuhan: Wuhan University Press, 2007: 116-135.<br />

Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

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Introduction<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Rough</strong> <strong><strong>Set</strong>s</strong><br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

<strong>Interval</strong>-<strong>valued</strong> . . .<br />

Approximation . . .<br />

References<br />

Thanks!<br />

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