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Introduction Background Clustering algorithm Results and discussion A Novel Clustering Algorithm in a Neutrosophic Recommender System for Medical Diagnosis Le Hoang Son Vietnam National University, Hanoi, Vietnam 23/03/2017 VNU - 23/03/2017 1 / 110

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Page 1: A Novel Clustering Algorithm in a Neutrosophic Recommender ... fileIntroductionBackgroundClustering algorithmResults and discussionConclusion and future work A Novel Clustering Algorithm

Introduction Background Clustering algorithm Results and discussion Conclusion and future work

A Novel Clustering Algorithm in aNeutrosophic Recommender System for

Medical Diagnosis

Le Hoang Son

Vietnam National University, Hanoi, Vietnam

23/03/2017

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Content

1. Introduction2. Background

2.1. Algebraic structures in neutrosophic recommender systems2.2. Neutrosophic similarity degree and neutrosophic similarity

matrix

3. A clustering algorithm for neutrosophicrecommender systems

4. Experimental result

5. Conclusion

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Introduction

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Medical Diagnosis

Medical diagnosis is a procedure for the investigation of a personssymptoms on the basis of disease.

Received the full attention of both the computer science and appliedcomputer mathematics research society.

Often contains a huge amount of uncertain, inconsistent,incomplete, and indeterminate data which are very difficult toretrieve [28].

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Neutrosophic Set and Neutrosophic Recommender System

Neutrosophic Set:

Proposed by Smarandache [27].Can handle the uncertain, incomplete and inconsistentinformation.

Neutrosophic Recommender System:

A recommender system base on neutrosophic set.Ability of solving problem which involves a large amount ofuncertain, inconsistent, incomplete and indeterminate datathat are notably difficult to retrieve, handle and process.

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Background

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Medical Diagnosis

Suppose that:

℘= {p1,p2, ...,pn},Γ = {s1,s2, ...sm},D = {d1,d2, ...,dk}

is the three lists of patients, symptoms and diseases, respectivelysuch that m,n,k ∈ N+ are the numbers of patients, symptoms anddiseases, respectively.

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Medical Diagnosis

Suppose that:

ℜ℘Γ = {ℜ℘Γ(pi ,sj) : ∀i = 1,2, ...,n; j = 1,2,3...m}

is the set of relations between patients and symptoms whereℜ℘Γ(pi ,sj) is the level of the patient pi who acquires the symptomsj . The value of ℜ℘Γ(pi ,sj) is either numeric number or aneutrosophic number which depends on the proposed domain ofthe problem.

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Medical Diagnosis

And:

ℜΓD = {ℜΓD(si ,dj) : ∀i = 1,2, ...,m; j = 1,2,3...k}

is the set which represents the relationship between the symptomsand the diseases where ℜΓD reveals the probability that symptomsi leads to dj the disease.We obtain:

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Medical Diagnosis

Definition 1

Medical diagnosis is the process of determining the relationshipbetween the patients and the diseases described asℜ℘D = {ℜ℘D(pi ,dj) : ∀i = 1,2, ...,n; j = 1,2,3...k} where the valueof ℜ℘D(pi ,dj) is either 0 or 1 which indicates that the patient piacquired the disease dj or not. Mathematically, the problem ofmedical diagnosis is an implication operator given by the mapping{ℜ℘Γ,ℜΓD}→ℜ℘D .

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Neutrosophic Set and Simplified Neutrosophic Set

Definition 2

Neutrosophic Set: Let X be a non-empty set and x ∈ X . Aneutrosophic set A in X is characterized by a truth membershipfunction TA, an indeterminacy membership function IA, and afalsehood membership function FA. TA(x), IA(x) and FA(x) arereal standard or non-standard subsets of ]−0,1+[ such that TA, IA,FA → ]−0,1+[.

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Neutrosophic Set and Simplified Neutrosophic Set

There is no restriction on the sum of TA(x), IA(x) and FA(x),so, ]−0 < TA(x) + IA(x) +FA(x) < 3+[.

From a philosophical point view, the neutrosophic set takesthe value from real standard or non-standard subsets of]−0,1+[. Thus, it is necessary to take the interval [0,1] insteadof ]−0, 1+[ in technical applications because it is difficult touse ]−0,1+[ in real life applications such as engineering andscientific problems.

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Neutrosophic Set and Simplified Neutrosophic Set

If the functions TA(x), IA(x) and FA(x) are singletonsubinterval/subsets of the real standard such that withTA(x) : X → [0,1], IA(x) : X → [0,1],FA(x) : X → [0,1]. Asimplification of the neutrosophic set A is denoted by:

(1) A = {(x ,TA(x), IA(x),FA(x)) : x ∈ X}.

with 0 < TA(x) + IA(x) +FA(x) < 3 and is a subclass of theneutrosophic set known as simplified neutrosophic set. Asimplified neutrosophic set contains the concept of the intervalneutrosophic set and the single valued neutrosophic set.

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Neutrosophication

Definition 3

The main purpose of neutrosophication is to map the inputvariables into neutrosophic input sets. If x is a crisp input, then

where x ∈ X and aj ≤ x ≤ ak for truth membership, bj ≤ x ≤ bk forindeterminacy membership, cj ≤ x ≤ ck for falsehood membership,respectively, and j ,k = 1,2,3,4.

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Deneutrosophication

Definition 4

This step is similar to defuzzification in [10] and involves thefollowing two stages:Stage 1: SynthesizationIn this stage, we transform a neutrosophic set Hk into a fuzzy setB by using the following function

(2) f = (THk (y), IHk (y),FHk (y)) : [0,1]× [0,1]× [0,1]→ [0,1]

where f is defined by:

(3) TB(y) = ε1 ∗THk (y) + ε2 ∗IHk (y)

2+ ε3 ∗

FHk (y)

4

and where 0≤ ε1,ε2,ε3 ≤ 1 such that ε1 + ε2 + ε3 = 1.

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Deneutrosophication

Definition

Stage 2: Typical neutrosophic valueIn this stage, we calculate a typical deneutrosophicated valueden(TB(y)) using the centroid or center of gravity method, whichis given below:

(4) den(TB(y)) =

∫ ba TB(y)ydy∫ ba TB(y)dy

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Single-criterion neutrosophic recommender system (SC-NRS)

Definition 5

The SC-NRS is a utility function ℜ, which is a mapping defined on(X ,Y ) and as follows

where TiX (x), IiX (x),FiX (x) are the truth membership function,indeterminate membership function and false membership functionof the patient with the linguistic label i th of the feature X suchthat i = 1,2, ...,s and TiX (x), IiX (x),FiX (x) ∈ [0,1] .

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Single-criterion neutrosophic recommender system (SC-NRS)

Similarly,

TjY (y), IjY (y),FjY (y)

is the truth membership function, indeterminate membershipfunction and false membership function of the symptom with thelinguistic label j th of the feature Y where

i = 1,2, ...,s and TjY (y), IjY (y),FjY (y) ∈ [0,1].

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Single-criterion neutrosophic recommender system (SC-NRS)

And,

TlD(d), IlD(d),FlD(d)

is the truth membership function, indeterminate membershipfunction and false membership function of the disease D with thelinguistic label l th where

l = 1,2, ...,s and TlD(d), IlD(d),FlD(d) ∈ [0,1].

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Multi-criteria neutrosophic recommender system (MC-NRS)

Definition 6

The MC-NRS is a utility function ℜ which is a mapping defined on(X ,Y ) and as follows

where T , I ,F are defined similarly as in SC-NRS.

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Algebraic structures in neutrosophic recommender systems

Proposition 1

The structure (F (NRS),∩,∪,NRSX×Y ,NRS /0) forms a completelattice.

Proof:

1) From commutative and associative properties [3] we obtainNRS1∩NRS2 = NRS12 ∈ F (NRS),NRS1∪NRS2 = NRS12 ∈ F (NRS).

2) From commutative and associative properties [3] we obtainNRS1∩NRS1 = NRS1 and NRS1∪NRS1 = NRS1.

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Algebraic structures in neutrosophic recommender systems

3) From the commutative and associative properties [3] we notethat

NRS1∩NRS2 = NRS2∩NRS1,NRS1∪NRS2 = NRS2∪NRS1,

NRS1∩ (NRS2∩NRS3) = (NRS1∩NRS2)∩NRS3,NRS1∪ (NRS2∪NRS3) = (NRS1∪NRS2)∪NRS3.

4) From the definition in [3] we obtainNRS1∩ (NRS2∪NRS1) = NRS1,NRS1∪ (NRS2∩NRS1) = NRS1.

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Thus from 1) to 4), we observe that the structure(F (NRS),∩,∪,NRSX×Y ,NRS /0) forms a lattice.Consider a collection of neutrosophic recommender systems{NRSi : i ∈ N} over F(NRS). We state,

∞⋂i=1

Xi ⊆ X ,∞⋂i=1

Yi ⊆ YwithXi ⊆ X ,Yi ⊆ Y

and

D∞l = {R∞

l ;T∞l ;F∞

l ; I∞l }= {R∞

lq;T∞lq ;F∞

lq ; I∞lq |q = 1,2, ...r ; l ∈N;k ∈N}

T∞lq = max{T 1

lq;T 2lq; ...};F∞

lq = min{F 1lq;F 2

lq; ...}; I∞lq = min{I 1

lq; I 2lq; ...}.

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This implies∞⋃i=1

NRSi ⊆ F (NRS)

Again, we obtain∞⋂i=1

NRSi ⊆ F (NRS)

Thus we have proven that F(NRS) is a complete lattice. �

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Proposition 2

The structure (F (NRS),∪,∩) is bounded distributive lattice.

Proof:From condition 4) in the above Proposition 1), we obtain

NRS1∩ (NRS2∪NRS3) = (NRS1∩NRS2)∪ (NRS1∩NRS3)

and

NRS1∪ (NRS2∩NRS3) = (NRS1∪NRS2)∩ (NRS1∪NRS3)

for all NRS1; NRS2; NRS3∈ F(NRS).This completes the proof. �

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Proposition 3

De Morgan LawsLet NRS1andNRS2 ⊆ F (NRS). Thus, the following conditionshold:

1) (NRS1∪NRS2)c = NRSc1 ∩NRSc

2 ,

2) (NRS1∩NRS2)c = NRSc1 ∪NRSc

2 .

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Proof: We only prove 1).

1) Because we obtain

(NRS1∪NRS2)c = NRSc12,

NRSc12 = {X c

12;Y c12;{D12c

l }|l = 1,2, ...,k},X c

12 = (X1∪X2)c = X c1 ∩X c

2 ,

Y c12 = Y c

1 ∩Y c2 ,

{D12cl }= (R12c

l ;T 12cl ;F 12c

l ; I 12cl ) =

{(R12clq ;T 12c

lq ;F 12clq ; I 12c

lq )|q = 1,2, ..., r ; l ∈ N;k ∈ N},T 12clq = F 12c

lq = min{F 1lq;F 2

lq};F 12clq = I 12c

lq = min{I 1lq; I 2

lq};I 12clq = T 12c

lq = max{T 1lq;T 2

lq}.

From the definition of NRSc1 ∩NRSc

2 the proposition is proved.

2) Provable on the same lines. �VNU - 23/03/2017 27 / 110

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Proposition 4

(F (NRS),∪,∩) forms a De Morgan algebra.

Proof: The proof follows from Proposition 2 and 3. �

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Algebraic structures in neutrosophic recommender systems

Proposition 5

(F (NRS),∪,∩,c ) forms a Boolean Algebra

Proof: From proposition 2 and proposition 3, we note that(F (NRS),∪,∩,c ) is a bounded distributive lattice andNRS1 ∈ F (NRS) with its complement NRSc

1 ∈ F (NRS) whichcompletes the proof. �

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Proposition 6

(F (NRS),∪,∩,c ,NRS /0) forms Kleen algebra.

Proof: From Proposition 4, (F (NRS),∪,∩,c ,NRS /0) forms DeMorgan algebra. Moreover

NRS1∩NRSc1 = NRS /0 ⊆ NRS2∪NRSc

2

with NRS1,NRS2 ∈ F (NRS). By the definition(F (NRS),∪,∩,c ,NRS /0) is a Kleen Algebra. �

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Proposition 7

(F (NRS),∩c ,NRSX×Y ) is a MV algebra.

Proof: To prove (F (NRS),∩c ,NRSX×Y ) is a MV algebra, wemust prove the following 4 conditions:

1) MV1: (F (NRS),∩) is a commutative monoid. This proof isstraightforward.

2) MV2: With every NRS1 ∈ F (NRS), we have (NRSc1 )c = NRS1

3) MV3: With NRS1andNRS2 we have(NRSX×Y )c ∩NRS1 = NRS /0 = (NRSX×Y )c

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Algebraic structures in neutrosophic recommender systems

4) MV4: Because,

(NRSc1 ∩NRS2)c ∩NRS3 = ((NRSc

1 )c ∪NRSc2 )∩NRS2

= (NRS1∪NRSc2 )∩NRS2

= (NRS1∩NRS2)∪ (NRSc2 ∩NRS2)

= (NRS1∩NRS2)∪NRS /0

= (NRS2∩NRS1)∪ (NRSc1 ∩NRS1)

= (NRS2∩NRSc1 )∪NRS1

for all NRS1,NRS2 ∈ F (NRS). Thus (F (NRS),∩c ,NRSX×Y ) isa MV algebra. �

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Proposition 8

(F (NRS),∪c ,NRS /0) also forms a MV algebra.

Proof: MV1, MV2, MV3 are straightfoward. We prove MV4:Because,

(NRSc1 ∪NRS2)c ∪NRS3 = ((NRSc

1 )c ∩NRSc2 )∪NRS2

= (NRS1∪NRS2)∩ (NRSc2 ∪NRS2)

= (NRS1∪NRS2)∩ (NRSX×Y )

= (NRS1∪NRS2)∩ (NRSc1 ∪NRS1)

= (NRS1∪NRS2)∩ (NRS1∪NRSc1 )

= (NRS2∩NRSc1 )∪NRS1

= (NRSc2 ∪NRS1)c ∪NRS1

For all NRS1,NRS2 ∈ F (NRS). Thus (F (NRS),∪c ,NRS /0) is a MValgebra. �

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Proposition 9

(F (NRS), |–|,NRS /0) is a bounded BCK algebra.

Proof: For any NRS1,NRS2,NRS3 ∈ F (NRS),

1) BCI-1:((NRS1|–|NRS2)|–|(NRS1|–|NRS3)|–|(NRS2|–|NRS3)) = NRS /0

2) BCI-2:(NRS1|–|(NRS1|–|NRS2))|–|NRS2 = NRS /0

3) BCI-3:NRS1|–|NRS2 = NRS /0

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4) BCI-4:LetNRS1|–|NRS2 = NRS /0;NRS2|–|NRS1 = NRS /0and this implies that NRS1 = NRS2

5) BCI-5:NRS /0|–|NRS2 = NRS /0Thus (F (NRS), |–|,NRS /0) is a BCK algebra. AdditionallyNRSX×Y is such that:NRS1|–|NRSX×Y = NRS /0 for all NRS1 ∈ F (NRS).

Therefore (F (NRS), |–|,NRS /0) is a bounded BCK algebra. �

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Algebraic structures in neutrosophic recommender systems

Definition 7

Let (F (NRS),∪,∩,c ) be a bounded lattice and NRS1 ∈ F (NRS).An element NRSc

1 is known as a pseudo-complement of NRS1 , ifNRS1∩NRSc

1 = NRS /0 and NRS2 ⊆ NRSc1 whenever

NRS1∩NRS2 = NRS /0. If every element of a lattice F(NRS) is apseudo-complement, then F(NRS) is said to bepseudo-complemented. The equation NRSc

1 ∪NRS = NRSX×Y isknown as the Stones identity.

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Algebraic structures in neutrosophic recommender systems

Definition 8

A Stone algebra is a pseudo-complemented, distributive latticesatisfying the Stones identity.

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Algebraic structures in neutrosophic recommender systems

Lemma 1

Let NRS1,NRS2 ∈ F (NRS). Thus, the pseudo-complement ofNRS1 relative to NRS2 exists in F(NRS).

Lemma 2

Let NRS1,NRS2 ∈ F (NRS). Thus, the pseudo-complement ofNRS2 relative to NRS1 exists in F(NRS).

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Algebraic structures in neutrosophic recommender systems

Proposition 10

(F (NRS),∪,∩,c ) forms Brouwerian lattices.

Proof: The proof follows from Lemma 1 and Lemma 2. �

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Neutrosophic similarity degree and neutrosophic similarity matrix

Definition 9

Let F(NRS) denotes the family of all neutrosophic recommendersystems. We define a mapping Θ : F (NRS)×F (NRS)→ F (NRS),where NRSj ∈ F (NRS) for all j = 1,2, .... Thus, Θ is is referred toas the neutrosophic recommender similarity degree (NRSD) ofNRS1 and NRS2 if Θ satisfies the following conditions.

1 Θ(NRS1,NRS2) is a neutrosophic value (NV).

2 Θ(NRS1,NRS2) = (1,0,0) if NRS1 = NRS2.

3 Θ(NRS1,NRS2) = Θ(NRS2,NRS1).

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We propose a formula to compute the NRSD of NRS1 and NRS2

(7)

Θ(NRS1,NRS2) = 1−

n

∑j=1

wj

β1|TNRS1(xj)−TNRS2(xj)|γ

+β2|INRS1(xj)− INRS2(xj)|γ

+β3|FNRS1(xj)−FNRS2(xj)|γ

1

γ

where β1, β2 and β3 are coefficients of the truth, interdeterminacyand falsehood memberships of NRS respectively and are normallyset as 1 by default. In addition,

γ ≥ 1,w = (w1,w2, ...,wn)t ,wj ∈ [0,1] with the conditionn

∑j=1

wj = 1

for all j = 1,2,3, ...,n and xj ∈ X .

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The above Eq.(7) has the ability to weight the deviation of NRSjfor each j = 1,2,3, ...,n as well as the deviation of the respectivetruth membership function, indeterminate membership functionand falsehood membership function which are highly flexible in thisaspect. However, if we conside Θ as the function of w, then itbecomes a bounded function. For instance

(8) ∂ (w) =

n

∑j=1

wj

β1|TNRS1(xj)−TNRS2(xj)|γ

+β2|INRS1(xj)− INRS2(xj)|γ

+β3|FNRS1(xj)−FNRS2(xj)|γ

where γ ≥ 1.

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Solving Eq. (8) for the maximum and minimum problems of Eq.(7), we obtain

(9) ∂ (w) =

n

∑j=1

wj

β1|TNRS1(xj)−TNRS2(xj)|γ

+β2|INRS1(xj)− INRS2(xj)|γ

+β3|FNRS1(xj)−FNRS2(xj)|γ

≤maxj

β1|TNRS1(xj)−TNRS2(xj)|γ

+β2|INRS1(xj)− INRS2(xj)|γ

+β3|FNRS1(xj)−FNRS2(xj)|γ

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A positive integer k always exists such that

(10) maxj

β1|TNRS1(xj)−TNRS2(xj)|γ

+β2|INRS1(xj)− INRS2(xj)|γ

+β3|FNRS1(xj)−FNRS2(xj)|γ

=

β1|TNRS1(xk)−TNRS2(xk)|γ

+β2|INRS1(xk)− INRS2(xk)|γ

+β3|FNRS1(xk)−FNRS2(xk)|γ

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Thus the equality holds only when wk = 1 and wj = 0 for j 6= k.Again by the definition of boundedness, we obtain

(11) ∂ (w) =

n

∑j=1

wj

β1|TNRS1(xj)−TNRS2(xj)|γ

+β2|INRS1(xj)− INRS2(xj)|γ

+β3|FNRS1(xj)−FNRS2(xj)|γ

≥minj

β1|TNRS1(xj)−TNRS2(xj)|γ

+β2|INRS1(xj)− INRS2(xj)|γ

+β3|FNRS1(xj)−FNRS2(xj)|γ

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Again, a positive integer s exists such that

(12) minj

β1|TNRS1(xj)−TNRS2(xj)|γ

+β2|INRS1(xj)− INRS2(xj)|γ

+β3|FNRS1(xj)−FNRS2(xj)|γ

=

β1|TNRS1(xs)−TNRS2(xs)|γ

+β2|INRS1(xs)− INRS2(xs)|γ

+β3|FNRS1(xs)−FNRS2(xs)|γ

The equality holds only when ws = 1 and wj = 0 for j 6= s.

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We denote¯∂ (NRS1,NRS2) as the lower bound and ∂̄ (NRS1,NRS2)

as the upper bound where

(13)¯∂ (NRS1,NRS2) = min

j

β1|TNRS1(xj)−TNRS2(xj)|γ

+β2|INRS1(xj)− INRS2(xj)|γ

+β3|FNRS1(xj)−FNRS2(xj)|γ

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And

(14) ∂̄ (NRS1,NRS2) = maxj

β1|TNRS1(xj)−TNRS2(xj)|γ

+β2|INRS1(xj)− INRS2(xj)|γ

+β3|FNRS1(xj)−FNRS2(xj)|γ

This statement implies that

1− γ√

¯∂ (NRS1,NRS2)≤Θ(NRS1,NRS2)≤ 1− γ

√∂̄ (NRS1,NRS2)

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Definition 10

Let NRS1 and NRS2 be two neutrosophic recommender systemsNRSs. Thus Θ(NRS1,NRS2) is said to be the neutrosophicrecommender similarity degree between NRS1 and NRS2 where

(15) Θ(NRS1,NRS2) =

(1− γ

√∂̄ (NRS1,NRS2),

γ√

¯∂ (NRS1,NRS2),

γ√

¯∂ (NRS1,NRS2)),

where γ ≥ 1 is an exponential coefficient that is set to 1 by default.

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Theorem 1

The similarity degree defined in Eq. (15) satisfies the condition ofneutrosophic recommender similarity degree.

Proof:1 We must prove that Θ(NRS1,NRS2) is a neutrosophic value.

For this purpose, we know that:

0≤ β1|TNRS1(xj)−TNRS2(xj)|γ + β2|INRS1(xj)− INRS2(xj)|γ

+ β3|FNRS1(xj)−FNRS2(xj)|γ

≤ (β1 + β2 + β3)max(|TNRS1(xj)−TNRS2(xj)|γ

+ |INRS1(xj)− INRS2(xj)|γ + |FNRS1(xj)−FNRS2(xj)|γ )

= max(|TNRS1(xj)−TNRS2(xj)|γ + |INRS1(xj)− INRS2(xj)|γ

+ |FNRS1(xj)−FNRS2(xj)|γ )

≤ 1

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which implies that

(16)

0≤ 1− γ√

¯∂ (NRS1,NRS2)≤ 1and0≤ 1− γ

√∂̄ (NRS1,NRS2)≤ 1

Because γ√

¯∂ (NRS1,NRS2), γ

√∂̄ (NRS1,NRS2) are the respective

lower and upper bounds, therefore

(17) 0≤ 1− γ√

¯∂ (NRS1,NRS2)≤ 1

(18) 0≤ 1− γ

√∂̄ (NRS1,NRS2)≤ 1

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which means

(19) 0≤ 1− (γ

√∂̄ (NRS1,NRS2)−2 γ

√¯∂ (NRS1,NRS2))≤ 3

Hence Θ(NRS1,NRS2) is a neutrosophic value.

2) Comparing both sides, we obtain

(20) 1− γ

√∂̄ (NRS1,NRS2) = 1, γ

√¯∂ (NRS1,NRS2) = 0

And we state(21)

1− γ√

¯∂ (NRS1,NRS2)≤Θ(NRS1,NRS2)≤ 1− γ

√∂̄ (NRS1,NRS2)

This gives us Θ(NRS1,NRS2) = 1 when NRS1 = NRS2.

3) This is obvious. �

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We associate a matrix to represent this similarity degree. For thispurpose, we define the following.

Definition 11

Let M =

xjksjkdjk

3n×n

be a 3n×n matrix. Thus, M is known as a

neutrosophic recommender matrix (NRM) if all of its entitiesxjk ,sjk ,djk(j ,k = 1,2, ...,n) are neutrosophic values.

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Definition 12

Let M1 =

x(1)jk

s(1)jk

d(1)jk

3n×n

and M2 =

x(2)jk

s(2)jk

d(2)jk

3n×n

be two NRM matrices.

Thus M = M1 •M2 is referred to as the composition of M1 and M2,

where

(22)

xjk =n∨

l=1

(x(1)jl ∧x

(2)lk ) =

maxj{min(T

x(1)jl

,Tx

(2)lk

)},minj{max(I

x(1)jl

, Ix

(2)lk

)},

minj{max(F

x(1)jl

,Fx

(2)lk

)}

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And:

sjk =n∨

l=1

(s(1)jl ∧s

(2)lk ) =

maxj{min(T

s(1)jl

,Ts

(2)lk

)},minj{max(I

s(1)jl

, Is

(2)lk

)},

minj{max(F

s(1)jl

,Fs

(2)lk

)}

djk =n∨

l=1

(d(1)jl ∧d

(2)lk ) =

maxj{min(T

d(1)jl

,Td

(2)lk

)},minj{max(I

d(1)jl

, Id

(2)lk

)},

minj{max(F

d(1)jl

,Fd

(2)lk

)}

where j ,k = 1,2, ...,n.

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Theorem 2

The composition matrix M = M1 •M2 is also a neutrosophicrecommender matrix.

Proof:This can be easily proved by Definition (12). �

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Definition 13

The neutrosophic recommender matrix M is known as aneutrosophic recommender similarity matrix (NRSM) if M fulfillsthe following criteria:

1 Reflexive: xjj = sjj = djj = (1,0,0) for j = 1,2, ...,n. .

2 Symetric: xjk = xkj ,sjk =s kj and djk = dkj which means thatthey are component-wise symmetric, i.e.,

Txjk = Txkj , Ixjk = Ixkj ,Fxjk = Fxkj

Tsjk = Tskj , Isjk = Iskj ,Fsjk = Fskj

Tdjk = Tdkj , Idjk = Idkj ,Fdjk = Fdkj

for all j ,k = 1,2, ...,n.

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Corollary 1

The composition of two NRSM matrices might not be an NRSM.

Proof:Straightforward. �

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Theorem 3

Let M1 be an NRSM matrix, and thus M = M1 •M1 is also anNRSM matrix.

Proof:Straightforward. �

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Theorem 4

Let M1, M2 and M3 be three NRSM matrices. Thus M1, M2 andM3 satisfies the associative law, i.e.,

(M1 •M2)•M3 = M1 • (M2 •M3).

Proof:

Let(M1 •M2)•M3 =

xjtsjtdjt

3n×n

andM1 • (M2 •M3) =

x ′jts ′jtd ′jt

3n×n

.

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By Definition (12), we know that

xjt =n∨

k=1

{(n∨

l=1

(x(1)jl ∧x

(2)lk ))∧x (3)

kt }

=n∨

k=1

n∨l=1

(x(1)jl ∧ (x

(2)lk ∧x

(3)kt ))

=n∨

l=1

{x (1)jl ∧ (

n∨k=1

(x(2)lk ∧x

(3)kt ))}

= x ′jt .

For j , t = 1,2, ...n . Similarly, we can prove this for s ′jt and d ′jtwhich completes the proof. �

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Corollary 2

Let M be an NRSM and let k1, k2 be any positive integers.Therefore,

Mk1+k2 = Mk1 •Mk2

where Mk1 and Mk2 are respectively the k1 and k2 compositions ofM and Mk1 , Mk2 and Mk1+k2 are NRSM.

Proof: Straightforward. �

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Definition 14

An NRSM M is known as a neutrosophic recommender equivalencematrix (NREM), if it satisfies the following assertions:

1 M is reflexive: xjj = sjj = djj = (1,0,0) for j = 1,2, ...,n.

2 M is symmetric: xjk = xkj ,djk = dkj ,sjk = skj forj ,k = 1,2, ...,n.

3 M is transitive: M2 ⊆M

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Theorem 5

Let M be an NRSM and let M →M2→M4→ ...→M2k → be itscompositions. After a finite time of compositions, there must exista positive integer k such that M2k = M2(k+1)

with M2k is an NREM.

Proof:This can be proved in a straightforward manner. �

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Definition 15

Let M =

xjksjkdjk

3n×n

be an NRSM, where xjk = (Txjk , Ixjk ,Fxjk ),

sjk = (Tsjk , Isjk ,Fsjk ) and djk = (Tdjk , Idjk ,Fdjk ) for j ,k = 1,2, ...,n.Thus, Xλ = (λxjk)n×n, Sλ = (λ sjk)n×n, Dλ = (λdjk)n×n is knownas the λ -cutting matrix of X, S and D, where

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Definition 16

The matrix M∗ is known as a neutrosophic equivalence matrix(NEM) if it satisfies the following conditions

1 Reflexive: x∗jk = s∗jk = d∗jk = 1 for j = 1,2, ...,n. and for anyx∗jk ,s

∗jk ,d

∗jk ∈ [0,1], j ,k = 1,2, ...,n.

2 Symmetric: x∗jk = x∗kj ,d∗jk = d∗kj ,s

∗jk = s∗kj for j ,k = 1,2, ...,n.

3 Transitive: maxl

(min(x∗jl ,x∗lk))≤ x∗jk ,max

l(min(s∗jl ,s

∗lk))≤

s∗jk ,maxl

(min(d∗jl ,d∗lk))≤ d∗jk for j ,k = 1,2, ...,n.

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Theorem 6

M =

xjksjkdjk

3n×n

is an NREM if its λ -cutting matrix

M∗ =

x∗jks∗jkd∗jk

3n×n

is an NEM, where x∗jk = (Tx∗jk, Ix∗jk ,Fx∗jk ),

s∗jk = (Ts∗jk, Is∗jk ,Fs∗jk ) and d∗jk = (Td∗jk

, Id∗jk ,Fd∗jk ) for j ,k = 1,2, ...,n..

Proof:Straightforward. �

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Definition 17

Let NRSj(j = 1,2, ...n) be a collection of neutrosophic

recommender systems, M =

xjksjkdjk

3n×n

be an NRSM,

M∗ =

x∗jks∗jkd∗jk

3n×n

be a NREM of M, and M∗λ

=

λx∗jkλ s∗jkλd∗jk

3n×n

be the

λ -cutting matrix of M∗. If the corresponding entries in both thej th line (column) and kth line (column) of M∗

λare equal, then

NRSj and NRSk are said to be of one type.

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Corollary 3

If NRSj and NRSk are of the same type, and NRSk and NRSl areof the same type, then NRSj and NRSl are of the same type.

Based on above theory, we develop a clustering algorithm forneutrosophic recommender systems in the next section.

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Suppose that:X = {x1,x2, ...,xn} is a finite set of alternatives (features),S = {s1,s2, ...,sn} is a set of attributes (symptoms) andD = {d1,d2, ...,dn} is a set of diseases in a multi-attributediagnostic decision-making problem.This section presents a new clustering algorithm for NRSs based onthe similarity matrices in the previous section.

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1) Step 1: Using the neutrosophication process in Def.(2), wetransform X = {x1,x2, ...,xn}, S = {s1,s2, ...,sn} andD = {d1,d2, ...,dn} into NSs and NRSs.

(24)

X = {(xj ,TX (xj), IX (xj),FX (xj))},S = {(sk ,TS(sk), IS(sk),FS(sk))},D = {(dl ,TD(dl), ID(dl),FD(dl))}.

where j ,k, l = 1,2, ...,p. In Eq. (24), TX (xj) represents thetruth degree of xj in X and IX (xj) represents theindeterminate degree of xj , and FX (xj) indicates the falsitydegree of xj in X. Similarly for S and D.

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2) Step 2: From the neutrosophic recommender similaritydegree in Eq. (15), we construct the neutrosophicrecommender similarity matrix

(25) M =

[xjk ]T

[sjk ]T

[djk ]T

3n×n

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where

xjk = Θ(xj ,xk) = [(1− ( γ

√∂̄ (xj ,xk))

TX,( γ

√¯∂ (xj ,xk))

IX,( γ

√¯∂ (xj ,xk))

FX

]

(26)

sjk = Θ(sj ,sk) = [(1− ( γ

√∂̄ (sj ,sk))

TS,( γ

√¯∂ (sj ,sk))

IS,( γ

√¯∂ (sj ,sk))

FS

]

(27)

djk = Θ(dj ,dk) = [(1− ( γ

√∂̄ (dj ,dk))

TD,( γ

√¯∂ (dj ,dk))

ID,( γ

√¯∂ (dj ,dk))

FD

]

(28)

where j ,k = 1,2, ...,n.

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In Eqs. (26), (27) and (28), we obtain

(29) γ

√¯∂ (xj ,xk) = min

l[β1|TXl

(xj)−TXl(xk)|γ + β2|IXl

(xj)− IXl(xk)|γ

+ β3|FXl(xj)−FXl

(xk)|γ ]

(30) γ

√∂̄ (xj ,xk) = max

l[β1|TXl

(xj)−TXl(xk)|γ + β2|IXl

(xj)− IXl(xk)|γ

+ β3|FXl(xj)−FXl

(xk)|γ ]

(31) γ

√¯∂ (sj ,sk) = min

l[β1|TSl (sj)−TSl (sk)|γ + β2|ISl (sj)− ISl (sk)|γ

+ β3|FSl (sj)−FSl (sk)|γ ]

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And:

(32) γ

√∂̄ (sj ,sk) = max

l[β1|TSl (sj)−TSl (sk)|γ + β2|ISl (sj)− ISl (sk)|γ

+ β3|FSl (sj)−FSl (sk)|γ ]

(33) γ

√¯∂ (dj ,dk) = min

l[β1|TDl

(dj)−TDl(dk)|γ + β2|IDl

(dj)− IDl(dk)|γ

+ β3|FDl(dj)−FDl

(dk)|γ ]

(34) γ

√¯∂ (dj ,dk) = max

l[β1|TDl

(dj)−TDl(dk)|γ ,β2|IDl

(dj)− IDl(dk)|γ

+ β3|FDl(dj)−FDl

(dk)|γ ]

where γ,β1,β2 and β3 are predefined parameters stated in Defs.(9-10) respectively.

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A clustering algorithm for neutrosophic recommender systems

3) Step 3: In this step, we must check whether M is aneutrosophic recommender equivalence matrix i.e. M2 ⊆M.If M is not, we must perform the compositionsM →M2→M4→ ...→M2k → ... until M2k = M2(k+1)

. Thus,M2k is the derived neutrosophic recommender equivalencematrix. Without loss of any generality, we denote it as

(35) M∗ =

x∗jks∗jkd∗jk

3n×n

where x∗jk = (Tx∗jk, Ix∗jk ,Fx∗jk ), s∗jk = (Ts∗jk

, Is∗jk ,Fs∗jk ) and

d∗jk = (Td∗jk, Id∗jk ,Fd∗jk ) for j ,k = 1,2, ...,n..

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A clustering algorithm for neutrosophic recommender systems

4) Step 4: For a given confidence level λ , we must calculate theλ -cutting matrix using Eq. (??)

(36) M∗λ

=

λx∗jkλ s∗jkλd∗jk

3n×n

5) Step 5: According to the λ -cutting matrix anddeneutrosophication process defined from Def. (10), the givenfinite set of alternatives (features) X = {x1,x2, ...,xn}, thegiven set of attributes (symptoms) S = {s1,s2, ...,sn} and thegiven set of diseases D = {d1,d2, ...,dn} have been clustered.

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Clustering model of neutrosophic recommender system

Figure 1: Clustering model of neutrosophic recommender system.

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Experimental result

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Experimental environment

Experimental Tools: The proposed algorithm wasimplemented in addition to the methods of Guo [12], Sahin[24], Ye 2014 [40] and Ye 2016 [43]. The algorithms were runin the Matlab 2015a programming language on a PC withIntel(R) Core (TM) i3 CPU [email protected] GHz, 4096MB RAMand the operating system was Windows 7 Professional 64 bits.

Datasets: Four benchmark datasets (RHC, diabetes, breastcancer and DMD) were taken from [6].

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Parameter settings:

Neutrosophication process: The values aj , bj and cj withj = 1,2,3,4 were chosen based on the mean and standarddeviation of each dataset. Suppose a dataset has the meanand standard deviation of first field µ and σ . Thus, (a1, a2,

a3, a4) is chosen as (µ-σ , µ-σ

2, µ+

σ

2, µ+σ). The reason for

the choice of these parameters is that each tuple in thedataset has a similar probability of taking on specific T, I andF values.

NRSM construction process: γ, β1, β2 and β3 were set to 1 bydefault.

λ -cutting process: The value of λ was randomly chosenbetween [0, 1]. We ran the code for several λ and took theaverage results.

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Experimental objective:

To compare the quality of all the clustering algorithms using threeindices: DB, SSWC and IVF [36]

Davies Bouldin (DB): Relates to the variance ratio criterion,which is based on the ratio between the distance of the innergroup and outer group. Particularly, the quality of thepartition is determined by the following formula:

(37) DB =1

k

k

∑l=1

Dl ,

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Experimental objective:

where:

(38) Dl = maxl 6=m{Dl ,m},

(39) Dl ,m = (d̄l + d̄m)/dm,l ,

where d̄l , d̄m are the average distances of clusters l andm,respectively, and dm,l is the distance between these clusters.

(40) d̄l =1

Nl∑xi∈Cl

||xi − x̄l ||;

The lower value of the DB criterion is better.

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Experimental objective:

Simplified silhouete width criterion (SSWC):

(41) SSWC =1

N

N

∑j=1

sxj ,

(42) sxj =bp,j −ap,j

max{ap,j ,bp,j}.

where ap,j is defined as the difference of object j relative to itscluster p. Similarly, dq,j is the difference of objects used to cluster jto q, q 6= p and bp,j . The idea is to replace the average distance bythe distance to the expected point.Using SSWC, a greater value shows more efficient algorithm.

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Experimental objective:

IFV:(43)

IFV =1

C

C

∑j=1

{ 1

N

N

∑k=1

u2kj [log2C −1

N

N

∑k=1

log2ukj ]2}× SDmax

σ̄D,

where:

(44) SDmax = maxk 6=j||Vk −Vj ||2,

(45) σ̄D =1

C

C

∑j=1

(1

N

N

∑k=1

||Xk −Vj ||2).

The maximal value of IFV indicates better performance.

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Clustering Result

(a) Sahin’s algorithm (b) Ye14’s algorithm

(c) Ye16’s algorithm (d) Our proposed algorithm

Figure 2: Clustering result of 4 methods with the diabetes dataset

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Clustering Result

(a) Sahin’s algorithm (b) Ye14’s algorithm

(c) Ye16’s algorithm (d) Our proposed algorithm

Figure 3: Clustering result of 4 methods with the breast dataset

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Clustering Result

(a) Sahin’s algorithm (b) Ye14’s algorithm

(c) Ye16’s algorithm(d) Our proposed algorithm

Figure 4: Clustering result of 4 methods with the RHC dataset

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Clustering Result

(a) Sahin’s algorithm (b) Ye14’s algorithm

(c) Ye16’s algorithm (d) Our proposed algorithm

Figure 5: Clustering result of 4 methods with the DMD dataset

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Comparative Results

Figure 6: Comparative results in diabetes dataset

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Comparative Results

Figure 7: Comparative results in breast dataset

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Comparative Results

Figure 8: Comparative results in RHC dataset

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Comparative Results

Figure 9: Comparative results in DMD dataset

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Comparative Results

Table 1: Comparative results of proposed method and existing methods(The values in bold font are the best for a given index and a dataset)

Dataset Method DB SSWC IFV

Average

Sahin 91.795 0.003 0.581Ye2014 25.360 0.070 108.383Ye2016 27.368 0.204 138.113

Our Method 21.426 0.267 232.362

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Table 2: Comparative time of the proposed method and existingmethods (sec)

Dataset No. of Data Sahin Ye14 Ye16 PM

Average

100 0.10 0.20 0.26 3.36200 0.32 0.85 1.38 13.28300 0.65 2.37 3.71 29.88400 1.07 4.98 8.85 62.04

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Conclusion and future work

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Conclusion

The results showed that our method outperforms the existingmethods in terms of clustering quality for all datasets.

The disadvantage is that the computational time of ourmethod is higher than those of the other methods.

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Future work

Improving the computational time of the clustering algorithm;

Designing a Bayesian-based approach to automaticallyestimate the parameter sets of the NRS and clusteringalgorithm;

Extending the NRS for multi-characteristic contexts;

Applying the multi-criteria NRS to solve sophisticatedproblems.

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Publication:

Thanh, N. D., Ali, M., Son, L. H. (2017). A Novel ClusteringAlgorithm in a Neutrosophic Recommender System for MedicalDiagnosis. Cognitive Computation, in press.

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Thank you for watching!

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References

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References I

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References II

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References III

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References IV

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[21] Mahdavi, M. M. (2012). Implementation of a recommender system on medicalrecognition and treatment. Int. J. e-Education, e-Business, e-Managemente-Learning 2(4), 315318.

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[23] Own, C. M. (2009). Switching between type-2 fuzzy sets and intuitionistic fuzzysets: an application in medical diagnosis. Appl. Intell. 31(3), 283291.

[24] Sahin R. (2014). Neutrosophic Hierarchical Clustering Algorithms. NeutrosophicSets and Systems, 2, 18-24.

[25] Samuel, A. E. & Balamurugan, M. (2012). Fuzzy maxmin composition techniquein medical diagnosis, Appl. Math. Sci. 6(35), 17411746.

[26] Shinoj, T. K., John, S. J. (2012). Intuitionistic Fuzzy Multi sets and itsApplication in Medical Diagnosis. World Acad. Sci. Eng. Technol. 6, 14181421.

[27] Smarandache, F. (1998). A Unifying Field in Logics. Neutrosophy: NeutrosophicProbability, Set and Logic, Rehoboth: American Research Press.

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References V

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[29] Szmidt, E., & Kacprzyk, J. (2003). An intuitionistic fuzzy set based approach tointelligent data analysis: an application to medical diagnosis. Proceeding ofRecent Advances in Intelligent Paradigms an Applications, 5770.

[30] Szmidt, E., & Kacprzyk, J. (2004). A similarity measure for intuitionistic fuzzysets and its application in supporting medical diagnostic reasoning. Proceeding ofArtificial Intelligence and Soft Computing 2004, 388-393.

[31] Son, L.H., Thong, N.T. (2015). Intuitionistic Fuzzy Recommender Systems: AnEffective Tool for Medical Diagnosis. Knowledge-Based Systems 74, 133150.

[32] Son, L.H., Tuan, T.M. (2016). A cooperative semi-supervised fuzzy clusteringframework for dental X-ray image segmentation. Expert Systems WithApplications 46, 380 393. bibitemThong1Thong, N.T., Son, L.H. (2015).HIFCF: An effective hybrid model between picture fuzzy clustering andintuitionistic fuzzy recommender systems for medical diagnosis. Expert SystemsWith Applications 42(7), 3682-3701.

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References VI

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[34] Tuan, T.M., Ngan, T.T., Son, L.H. (2016). A Novel Semi-Supervised FuzzyClustering Method based on Interactive Fuzzy Satisficing for Dental X-Ray ImageSegmentation. Applied Intelligence 45(2), 402-428.

[35] Tuan, T.M., Son, L.H. (2016). A novel framework using graph-based clusteringfor dental x-ray image search in medical diagnosis. International Journal ofEngineering and Technology 8(6), 422 427.

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References VII

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[40] Ye, J. (2014). A netting method for clustering-simplied neutrosophic information.Journal of Intelligent Systems 23(4), 379389.

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[42] Ye, J., & Fu, J. (2015). Multi-period medical diagnosis method using a singlevalued neutrosophic similarity measure based on tangent function. ComputerMethods and Programs in Biomedicine 123, 142-149.

[43] Ye, J. (2014). Clustering Methods Using Distance-Based Similarity Measures ofSingle-Valued Neutrosophic Sets. Journal of Intelligent Systems 23(4), 379-389.

[44] Yu, J., Rui, Y., Tang, Y. Y., & Tao, D. (2014). High-order distance-basedmultiview stochastic learning in image classification. IEEE transactions oncybernetics, 44(12), 2431-2442.

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References VIII

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[46] Yu, J., Yang, X., Gao, F., & Tao, D. (2017). Deep multimodal distance metriclearning using click constraints for image ranking. IEEE transactions oncybernetics, doi: 10.1109/TCYB.2016.2591583.

[47] Zhang, M., Zhang, L., & Cheng, H., Segmentation of ultrasound breast imagesbased on a neutrosophic method, Opt. Eng. 49(11) 117001, (2010), doi:10.1117/1.3505

[48] Zhang, H. Y., Ji, P., Wang, J. Q., & Chen, X. H. (2016). A neutrosophic normalcloud and its application in decision-making. Cognitive Computation, 8(4),649-669.

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