Доц. д-р Петър Василев | Публикации

Начало | Биография | Публикации

Избрани научни публикации

Монография

  • Atanassov, K., Vassilev, P. and R. Tsvetkov. Intuitionistic Fuzzy Sets, Measures and Integrals, Sofia, “Prof. Marin Drinov” Academic Publishing House, 2013.

Избрани статии

2023

  1. Popov, E., Georgieva, R., Dmitrenko, D., Bojkov, B, Slavov, C., Lubich, M., Vassilev, P., Atanassova, V., Todorova, L., Atanassov, K.. Generalized Net Model of the Prostate Cancer Early Stages of Development. 2nd International Symposium on Bioinformatics and Biomedicine, BioInfoMed 2022. Lecture Notes in Networks and Systems, 658, Springer, 2023, ISBN:978-303131068-3, DOI:10.1007/978-3-031-31069-0_24, 246-252. SJR (Scopus):0.151
  2. Vassilev, P. M., Todorova, L. P., Popov, E. P., Georgieva, R. N., Slavov, Ch. K., Atanassov, K. T.. Two New Modifications of the InterCriteria Analysis. Comptes Rendus de l’Academie Bulgare des Sciences, 76, 1, Prof. Marin Drinov Academic Publishing House, Sofia, Bulgaria, 2023, ISSN:1310-1331, DOI:10.7546/CRABS.2023.01.03, 23-34. JCR-IF (Web of Science):0.326
  3. Vassilev, P. M., Stoyanov, T., Todorova, L. P., Marazov, A., Andonov, V., Ikonomov, I.. Orderings over Intuitionistic Fuzzy Pairs Generated by the Power Mean and the Weighted Power Mean. Mathematics, 11, 13, MDPI, 2023, DOI:10.3390/math11132893, 2893. JCR-IF (Web of Science):2.4
  4. Angelova M.,, Roeva, O., P. Vassilev, T. Pencheva. Multi-population Genetic Algorithm and Cuckoo Search Hybrid Technique for Parameter Identification of Fermentation Processes Models. Processes, 11, MDPI, 2023, ISSN:2227-9717, DOI:https://doi.org/10.3390/pr11020427, 427. JCR-IF (Web of Science):3.5

2022

  1. Mavrov, D., Atanassova, V., Bureva, V., Roeva, O., Vassilev, P., Tsvetkov, R., Zoteva, D., Sotirova, E., Atanassov, K., Alexandrov, A., Tsakov, H. Application of Game Method for Modelling and Temporal Intuitionistic Fuzzy Pairs to the Forest Fire Spread in the Presence of Strong Wind. Mathematics, 10, 8, MDPI, 2022, DOI:10.3390/math10081280, 1280. SJR (Scopus):0.538, JCR-IF (Web of Science):2.592
  2. Lubich, M., Papazov, V., Popov, E., Georgieva, R., Dmitrenko, D., Bojkov, B., Slavov, C., Vassilev, P., Atanassova, V., Todorova, L., Atanassov, K. T. A Generalized Net Model of the Prostate Gland’s Functioning. Mathematics, 10, 3, MDPI, 2022, DOI:10.3390/math10030479, 479. SJR (Scopus):0.538, JCR-IF (Web of Science):2.592
  3. Ikonomov, N., Marinov, P., Vassilev, P., Roeva, O., Zoteva, D., Atanassova, V., Atanassov, K. 3D software implementation of the Game Method for Modelling forest fires in MyGL software tool. 16th National Conference on Operational and Systems Research (BOS/SOR) / 19th International Workshop on Intuitionistic Fuzzy Sets and Generalized Nets (IWIFSGN). Lecture Notes in Networks and Systems, Vol. 338: Uncertainty and imprecision in Decision Making and Decision Support, 338, Springer, 2022, DOI:10.1007/978-3-030-95929-6_25, 327-337. SJR (Scopus):0.15
  4. Bureva V., Sotirova E., Vassilev P., Atanassova, V., Roeva O., Atanassov, K, Tsakov H.. Application of Game Method for Modelling to Locate a Forest Fire Ignition Point in the Presence of Wind. Lecture Notes in Networks and Systems, 338, Springer, 2022, ISBN:978-303095928-9, ISSN:23673370, 280-293. SJR (Scopus):0.151
  5. Todorova, L, Ignatova, V, Vassilev, P, Surchev, J. Generalized Net Model of Computer Based Registration and Rehabilitation of Cognitive Impairments in Multiple Sclerosis. Lecture Notes in Networks and Systems, 338, Springer, 2022, ISSN:2367-3370, DOI:10.1007/978-3-030-95929-6_30, 397-407. SJR (Scopus):0.151
  6. Roeva O., Zoteva, D., Vassilev P.. Generalized Net Model of Coyote Optimization Algorithm. Int J Bioautomation, 26, 4, 2022, 353-360. SJR (Scopus):0.16
  7. Jereva D., Alov P., Tsakovska I., Angelova M., Atanassova V., Vassilev P., Ikonomov N., Atanassov K., Pajeva I., Pencheva T.. Application of InterCriteria Analysis to Assess the Performance of Scoring Functions in Molecular Docking Software Packages. Mathematics, 10, MDPI, 2022, DOI:10.3390/math10152549, 2549. SJR (Scopus):0.538, JCR-IF (Web of Science):2.592
  8. Atanassov, K., Marinov, E., Vassilev, P. An interval-valued intuitionistic fuzzy estimation of the area of 2D-figures based on Pick’s formula. 16th National Conference on Operational and Systems Research (BOS/SOR) / 19th International Workshop on Intuitionistic Fuzzy Sets and Generalized Nets (IWIFSGN). Lecture Notes in Networks and Systems, Vol. 338: Uncertainty and imprecision in Decision Making and Decision Support, 338, Springer, 2022, ISSN:2367-3370, DOI:10.1007/978-3-030-95929-6_7, 85-91. SJR (Scopus):0.51

2021

  1. Stratiev, D., Shishkova, I., Ivanov, M., Dinkov, R., Georgiev, B., Argirov, G., Atanassova, V., Vassilev, P., Atanassov, K., Yordanov, D., Popov, A., Padovani, A., Hartmann, U., Nenov, S.. Catalytic Cracking of Diverse Vacuum Residue Hydrocracking Gas Oils. Chemical Engineering and Technology, 44, 6, Wiley-VCH Verlag, 2021, DOI:10.1002/ceat.202000577, 997-1008. SJR (Scopus):0.441, JCR-IF (Web of Science):1.543
  2. Stratiev, D., Shishkova, I., Ivanov, M., Dinkov, R., Georgiev, B., Argirov, G., Atanassova, V., Vassilev, P., Atanassov, K., Yordanov, D., Popov, A., Padovani, A., Hartmann, U., Brandt, S., Nenov, S., Sotirov, S., Sotirova, E.. Role of Catalyst in Optimizing Fluid Catalytic Cracking Performance during Cracking of H-Oil-Derived Gas Oils. ACS Omega, 6, 11, American Chemical Society, 2021, ISSN:2470-1343, DOI:10.1021/acsomega.0c06207, 7626-7637. SJR (Scopus):0.767, JCR-IF (Web of Science):2.87
  3. Zoteva, D., Vassilev, P., Todorova, L., Atanassov, K., Doukovska, L., Tzanov, V.. Generalized Net Model of Cyber-control of the Firm’s Dumpers and Crushers. Studies in Big Data, 84, Springer, 2021, ISSN:2197-6503, DOI:10.1007/978-3-030-65722-2_15, 245-253. JCR-IF (Web of Science):0.147
  4. Vassilev, P., Todorova, L., Marinov, E.. On intuitionistic fuzziness. Book series Studies in Computational Intelligence, Research in Computer Science in the Bulgarian Academy of Sciences, 934, Studies in Computational Intelligence, 2021, DOI:10.1007/978-3-030-72284-5_11, 227-254. SJR (Scopus):0.185
  5. Vassilev, P., Atanassov, K.. A note on intuitionistic fuzzy sets, interval valued intuitionistic fuzzy sets and picture fuzzy sets. Advances in Intelligent Systems and Computing, 1081, Springer, 2021, ISSN:2194-5357, DOI:10.1007/978-3-030-47024-1_3, 24-28. JCR-IF (Web of Science):0.215
  6. Tsakovska I, Alov P, Ikonomov N, Atanassova V, Vassilev P, Roeva O, Jereva D, Atanassov K, Pajeva I, Pencheva T. InterCriteria Analysis Implementation for Exploration of the Performance of Various Docking Scoring Functions. Advances in High Performance Computing. HPC 2019. Studies in Computational Intelligence, 902, Springer, 2021, ISBN:978-3-030-55347-0, DOI:10.1007/978-3-030-55347-0_8, 88-98. SJR (Scopus):0.185
  7. Roeva, O., Vassilev, P., Ikonomov, N., Marinov, P., Zoteva, D., Atanassova, V., Atanassov, K.. MkBGFire Software – An Example of Game Modelling of Forest Fires in Bulgaria. Advances in Intelligent Systems and Computing, 1081, Springer, 2021, DOI:10.1007/978-3-030-47024-1_36, 387-397. SJR (Scopus):0.215
  8. Ribagin, S., Vassilev, P., Zoteva, D.. Generalized Net Model of an Active Elbow Orthosis Prototype. Advances in Intelligent Systems and Computing, 1081, Springer, 2021, ISSN:2194-5357, DOI:https://doi.org/10.1007/978-3-030-47024-1_18, 167-173. SJR (Scopus):0.22
  9. Jekova, I., Vassilev, P., Stoyanov, T., Pencheva, P.. InterCriteria Analysis: Application for ECG Data Analysis. Mathematics, 9, 8, MDPI, 2021, ISSN:2227-7390, DOI:10.3390/math9080854, 854. SJR (Scopus):0.538, JCR-IF (Web of Science):2.592
  10. Atanassov, K., Vassilev, P., Roeva, O.. Level operators over intuitionistic fuzzy index matrices. Mathematics, 9, 4, 2021, DOI:10.3390/math9040366, 366. SJR (Scopus):0.495, JCR-IF (Web of Science):2.258
  11. Atanassov, K., Vassilev, P., Atanassova, V., Roeva, O., Iliev, R., Zoteva, D., Bureva, V., Mavrov, D., Alexandrov, A.. Generalized Net Model of Forest Zone Monitoring by UAVs. Mathematics, 9, 22, MDPI, 2021, ISSN:2227-7390, DOI:https://doi.org/10.3390/math9222874, JCR-IF (Web of Science):2.258
  12. Stratiev, D., Nenov, S., Shishkova, I., Georgiev, B., Argirov, G., Dinkov, R., Yordanov, D., Atanassova, V., Vassilev, P., Atanassov, K.. Commercial Investigation of the Ebullated-Bed Vacuum Residue Hydrocracking in the Conversion Range of 55-93%. ACS Omega, 5, 51, American Chemical Society, 2020, DOI:10.1021/acsomega.0c05073, 33290-33304. SJR (Scopus):0.779, JCR-IF (Web of Science):2.87

2020

  1. Ignatova V., Surchev J., Stoyanova Ts., Vassilev P., Haralanov L., Todorova, L.. Social cognition impairments in patients with multiple sclerosis. Comparison with grade of disability.. Neurology India, 68, 1, 2020, ISSN:19984022, 94-98. JCR-IF (Web of Science):2.128
  2. Vassilev, P., Atanassov, K.. Generalised Atanassov Intuitionistic Fuzzy Sets Are Actually Intuitionistic Fuzzy Sets. Studies in Computational Intelligence, 862, Springer Nature, 2020, ISBN:978-3-030-35445-9, ISSN:1860-949X, 107-117. SJR (Scopus):0.185
  3. Atanassov, K., Vassilev, P.. Intuitionistic fuzzy sets and other fuzzy sets extensions representable by them. Journal of Intelligent & Fuzzy Systems, 38, 1, 2020, DOI:10.3233/JIFS-179426, 525-530. SJR (Scopus):0.331, JCR-IF (Web of Science):1.851
  4. Angelova, M., Vassilev, P., Pencheva, T.. Genetic Algorithm and Cuckoo Search Hybrid Technique for Parameter Identification of Fermentation Process Model. Int J Bioautomation, 24, 3, 2020, 277-288. SJR (Scopus):0.242

2019

  1. Roeva, O., Ikonomov, N., Vassilev, P.. Discovering Knowledge from Predominantly Repetitive Data by InterCriteria Analysis. Studies in Computational Intelligence, 795, Springer, 2019, 213-233. SJR (Scopus):0.183
  2. Roeva, O., Vassilev, P., Ikonomov, N., Angelova, M., Su, J., Pencheva, T.. On Different Algorithms for InterCriteria Relations Calculation. Studies in Computational Intelligence, 757, Springer, 2019, ISSN:1860-949X, 143-160. SJR (Scopus):0.215
  3. Atanassov, K., Roeva, O., Bureva, V., Chesmedjiev, P., Vassilev, P., Atanassova, V.. Operators over 3-Dimensional Index Matrices. The 6th IEEE International Conference “Big Data, Knowledge and Control Systems Engineering” (BdKCSE’2019), IEEE, 2019, 9010655
  4. Tomov, Z., Vassilev, P., Atanassov, K., Sotirov, S. Generalized Net Model of the process of n-th prime number calculation by different formulas. ANNA’18; Advances in Neural Networks and Applications 2018., VDE VERLAG GMBH ∙ Berlin ∙ Offenbach, 2018, ISBN:978-3-8007-4756-6, 68-72

2018

  1. Ikonomov, N., Vasilev, P., Roeva, O.. ICrAData – Software for InterCriteria Analysis. Int. J. Bioautomation, 22, 1, 2018, ISSN:1314-1902, DOI:10.7546/ijba.2018.22.1.1-10, 1-10. SJR (Scopus):0.267
  2. Vassilev, P., Stoyanov, T.. On Power Mean Generated Orderings Between Intuitionistic Fuzzy Pairs. Advances in Intelligent Systems and Computing, 643, Springer International Publishing AG, 2018, ISBN:978-3-319-66826-0, ISSN:2194-5357, DOI:10.1007/978-3-319-66827-7_44, 476-481. SJR (Scopus):0.174
  3. Vassilev, P., Ribagin, S.. A note on intuitionistic fuzzy modal-like operators generated by power mean. Advances in Intelligent Systems and Computing, 643, Springer, Cham, 2018, ISBN:978-3-319-66826-0, DOI:https://doi.org/10.1007/978-3-319-66827-7_43, SJR (Scopus):0.174
  4. Atanassova, V., Doukovska, L., Kacprzyk, A., Sotirova, E., Radeva, I., Vassilev, P. Intercriteria analysis of The Global Competitiveness Reports: from efficiency- to innovation-driven economies. Journal of Multiple-valued Logic and Soft Computing, 31, 5-6, Old City Publishing, 2018, ISSN:1542-3980 (print), 1542-3999 (online), 469-494. JCR-IF (Web of Science):0.667
  5. Atanassov, Krassimir, Vassilev, Peter. On the Intuitionistic Fuzzy Sets of n-th Type. Studies in Computational Intelligence, 738, Springer, Cham, 2018, ISBN:978-3-319-67945-7, ISSN:1860-949X, DOI:10.1007/978-3-319-67946-4_10, 265-274. SJR (Scopus):0.183
  6. Atanassov, Krassimir, Vassilev, Peter, Georgiev, Ivan, Tsakov, Hristo. Generalized net model of the organization of the firefighting activities when dealing with forest fires. ANNA’18; Advances in Neural Networks and Applications 2018., VDE VERLAG GMBH ∙ Berlin ∙ Offenbach, 2018, ISBN:978-3-8007-4756-6, 77-81
  7. Andreev, N., Vassilev, P., Atanassova, V., Roeva, O., Atanassov, K.. Generalized net model of the cooperation between the Departments of transfusion Haematology and the National Centre of transfusion Haematology. ANNA’18; Advances in Neural Networks and Applications 2018., VDE VERLAG GMBH ∙ Berlin ∙ Offenbach, 2018, ISBN:978-3-8007-4756-6, 82-85

2017

  1. Stefanova-Pavlova, M., Andonov, V., Stoyanov, T, Angelova, M., Cook, G., Klein, B., Vassilev, P, Stefanova, E.. Modeling Telehealth Services with Generalized Nets. Studies in Computational Intelligence, 657, Springer International Publishing Switzerland, 2017, ISBN:978-3-319-41437-9, ISSN:1860-949X, e-ISSN 1860-9503, 279-290. SJR (Scopus):0.187
  2. Vassilev, P. Intuitionistic Fuzzy Sets Generated by Archimedean Metrics and Ultrametrics. Studies in Computational Intelligence, 657, Springer International Publishing Switzerland, 2017, ISBN:978-3-319-41437-9, ISSN:ISSN 1860-949X, e-ISSN 1860-9503, 339-378. SJR (Scopus):0.187
  3. Roeva O., P. Vassilev, P. Chountas. Application of Topological Operators over Data from InterCriteria Analysis. Lecture Notes in Artificial Intelligence, subseries of Lecture Notes in Computer Science, 10333, Springer, 2017, ISBN:978-3-319-59691-4, DOI:10.1007/978-3-319-59692-1 19, 215-225. SJR (Scopus):0.295

2016

  1. Marinov E., Vassilev, P., Atanassov, K.. On Separability of Intuitionistic Fuzzy Sets. Novel Developments in Uncertainty Representation and Processing, series Advances in Intelligent Systems and Computing, 401, Springer, 2016, 111 – 123
  2. Pencheva, T., Angelova, M., Vassilev, P., Roeva, O.. InterCriteria Analysis Approach to Parameter Identification of a Fermentation Process Model. Novel Developments in Uncertainty Representation and Processing, series Advances in Intelligent Systems and Computing, 401, Springer, 2016, 385 – 389
  3. Roeva, O., Vassilev, P.. InterCriteria Analysis of Generation Gap Influence on Genetic Algorithms Performance. Novel Developments in Uncertainty Representation and Processing, series Advances in Intelligent Systems and Computing, 401, Springer, 2016, ISBN:978-3-319-26210-9, DOI:10.1007/978-3-319-26211-6_26, 301 – 313
  4. Todorova L., P. Vassilev, J. Surchev. Using Phi Coefficient to Interpret Results Obtained by InterCriteria Analysis. Advances in Intelligent Systems and Computing, 401, Springer, 2016, 231 – 239
  5. Todorova, L.,, Ignatova, V., Hadjitodorov, S, Vassilev, P.. Generalized Net Model for Monitoring the Degree of Disability in Patients with Multiple Sclerosis Based on Neurophysiologic Criteria. “Studies in Fuzziness and Soft Computing”, Springer Series, 332, Springer, 2016, ISSN:1434-9922, DOI:10.1007/978-3-319-26302-1_18, 289 – 303

2015

  1. Roeva O., Vassilev P., Angelova M., Pencheva T.. InterCriteria Analysis of Parameters Relations in Fermentation Processes Models. Lecture Notes in Computer Science, 9330, Springer, 2015, ISBN:978-3-319-24305-4, 171 – 181. SJR:0.34
  2. Marinov, Evgeniy, Vassilev, Peter, Atanassov, Krassimir. On Intuitionistic Fuzzy Metric Neighbourhoods. 9th Conference of the European Society for Fuzzy Logic and Technology (EUSFLAT), 30.06-03.07.2015, Gijon, Spain, Atlantis Press, 2015, ISBN:978-94-62520-77-6, ISSN:1951-6851, DOI:10.2991/ifsa-eusflat-15.2015.226, 1585 – 1591
  3. Roeva, O., S. Fidanova, Vassilev, P., P. Gepner. InterCriteria Analysis of a Model Parameters Identification using Genetic Algorithm. Annals of Computer Science and Information Systems, 5, 2015, DOI:10.15439/2015F223, 501 – 506
  4. Vassilev, P. A note on new distances between intuitionistic fuzzy sets. Notes on Intuitionistic Fuzzy Sets, 21, 5, Publishing House of the Bulgarian Academy of Sciences, 2015, ISSN:1310-4926, 11 – 15
  5. Vassilev P., L. Todorova, V. Andonov. An auxiliary technique for InterCriteria Analysis via a three dimensional index matrix. Notes on Intuitionistic Fuzzy Sets, 21, 2, 2015, 71 – 76

2014

  1. Vassilev, P. On an estimate from above for the remainder sum of certain series related to Euler’s gamma function. Advanced Studies in Contemporary Mathematics (Kyungshang), Vol 24(1), 2014, 109-128.
  2. Vassilev, P., L. Todorova, K. Kosev. Note on the (μ, ν)-coherence relation, defined over Intuitionistic Fuzzy Sets. Notes on Intuitionistic Fuzzy Sets, 4, 20, 2014, 7 – 9

2013

  1. Todorova, L., P. Vassilev, M. Matveev, V. Krasteva, I. Jekova, S. Hadjitodorov, G. Georgiev, S. Milanov. (2013). Generalized net model of a protocol for weaning from mechanical ventilation. Comptes rendus de l’Acad`emie bulgare des Sciences, Vol 66, 10, 1385-1392.

2012

  1.  Parvathi, R., P. Vassilev, K. Atanassov. A note on the bijective correspondence between intuitionistic fuzzy sets and intuitionistic fuzzy sets of p-th type. In: -New Developments in Fuzzy Sets, Intuitionistic Fuzzy Sets, Generalized Nets and Related Topics. Volume I: Foundations, SRI PAS IBS PAN, Warsaw, 2012, 143-147.
  2. Jekova I., V. Krasteva , G. Georgiev, L. Todorova, P. Vassilev and M. Matveev. Measurements on Ventilatory Signals during Volume Controlled and Pressure Support Ventilation to Predict the Weaning Outcome. Annual Journal of Electronics, Vol. 6 (1), 2012, 27-30.
  3. Vassilev, P. Intuitionistic Fuzzy Sets with Membership and Non-membership Functions of Exponential Type. In: Vol. 2 of Proc. of IEEE 6th Conference on Intelligent Systems, 6-8 September, Sofa, 2012, 145-149.
  4. Todorova L, J. Surchev, P. Vassilev, P. Hadjistoykov. Application of Intuitionistic Fuzzy Sets for More Objective Comparison of Kaplan-Meier Curves. In: Vol. 2 of Proc. of IEEE 6th Conference on Intelligent Systems, 6-8 September, Sofa, 2012, 212-215.
  5. Vassilev, P. On the intuitionistic fuzzy sets with metric type relation between the membership and non-membership functions.Proc. of 16th Int. Conf. on IFSs, Sofia, 9–10 Sept. 2012. Notes on Intuitionistic Fuzzy Sets Vol. 18, 2012, No. 3, 30–38.
  6. Pavlov. Y, P. Vassilev, Preferences and determination of the nominal growth rate of fed-batch process: control design of complex processes, Biotechnology and Biotechnological Equipment, Vol 26(5), 2012, 3254-3259.
  7. Parvathi, R., S. Hadjitodorov, K. Atanassov, P. Vassilev, Generalized net model of an intuitionistic fuzzy clustering technique for biomedical data, Biotechnology and Biotechnological Equipment, Vol 26(5), 2012, 3306-3309.

2011

  1. Vassilev, P. A note on distance and similarity measures between intuitionistic fuzzy sets. Notes on Intuitionistic Fuzzy Sets, Vol. 17 (2), 2011,68-74

2010

  1. Vassilev, P. On reassessment of expert evaluations in the case of intuitionistic fuzziness. Advanced Studies in Contemporary Mathematics, Vol. 20(4), 2010, 569-574.
  2. Vassilev, P. On One Trinomial Equation and Its Solution, Advanced Studies in Contemporary Mathematics, Vol. 20(4), 2010, 489-497
  3. Todorova, L., P. Vassilev. Algorithm for Clustering Data Set Represented by Intuitionistic Fuzzy Estimates. Int.J.Bioautomation, Vol. 14 (1), 2010, 61-68
  4. Todorova L., P. Vassilev, E. Szmidt, S. Hadjitodorov. Spatial interpretation of Operators over Intuitionistic Fuzzy Sets. Issues in Intuitionistic Fuzzy Sets and Generalized Nets, Vol. 8, 2010, 8-18.
  5. Tcheshmedjiev, P., P. Vassilev. Determining intuitionistic fuzzy degree of overlapping of computation and communication in parallel applications using generalized nets. Issues in Intuitionistic Fuzzy Sets and Generalized Nets, Vol. 8, 2010, 50-57.

2009

  1. Vassilev P., L.Todorova. Generalized Net Model of a K-Nearest Neighbor Rule Pattern Recognition Algorithm for the Case of Intuitionistic Fuzzy Sets. Proceedings of the Tenth International Workshop on Generalized Nets (K, Atanassov and А. Shannon, Eds.), Sofia, 5 Dec. 2009, 8-13
  2. Vassilev, P. Subnorms, Non-Archimedean Field Norms and Their Corresponding d-FS and d-IFS. Cybernetics and Information Technologies, Vol. 9 (2), 2009, 30-37.
  3. Parvathi, R., P. Vassilev and Krassimir Atanassov. New topological operators over intuitionistic fuzzy sets, Advanced Studies in Contemporary Mathematics, 18 (1), 2009, 49-57