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$\begingroup$Can you help me also knowing how to make the input using the { as it is shown in the top of the question? I mean, how can I input the "kind of" matrix" By default in the "special character section" appears an option 2x2 (Typographic composition section) there are shortcuts for expanding the rows and columns but they do not work correctly. And I am working on Mac so shortcuts do not work either.$\endgroup$