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This is a text from a math textbook. I just wonder how to type the "italic" symbols given in the text using Latex (I do not even know the names of the symbols...) For example how to type the symbol resembling H(appearing in the end of the first line)? Also, how to type the symbol right next to the word "Banach space" in the second line? How about the symbol resembling B(H) in the fourth line? I have no ideas..Could anyone tell me?