• @affiliateOP
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      281 year ago

      × is the cartesian product and = {x, {x,y}} is the ordered pair of x and y. (i.e., if x is in X and y is in Y, then is the corresponding element of the cartesian product X × Y). hope this helps

        • @affiliateOP
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          251 year ago

          it’s the “order type” of a well ordering on a set. so, given a set X with a total ordering R, type(X,R) is the unique ordinal isomorphic to (X,R)

            • @affiliateOP
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              151 year ago

              yeah but sometimes when the textbook authors are feeling particularly mischievous they’ll just put them in random places. and sometimes they’ll even skip the proofs but keep the square.

          • Lem Jukes
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            fedilink
            81 year ago

            Give it up for op actually out here answering questions like a real live teacher.

    • Jack Riddle
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      fedilink
      51 year ago

      × is the cartesian product I think, no clue what the other thing is tho