Essential numerical ranges of operators in semi-Hilbertian spaces

Amir Baklouti1, Mohamed Mabrouk2
1Department of Mathematics, College of first Common year, Umm Al-Qura University, P.O. Box 14035, 21955, Mecca, Saudi Arabia
2Department of Mathematical Science, Faculty of Applied Science, Umm Al-Qura University, P. O. Box 14035, 21955, Mecca, Saudi Arabia

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