Row-and-column enumeration of an ordinal square

ID: row-and-column-enumeration-of-an-ordinal-square

A compatible transfinite family of bijections can enumerate the square of an ordinal by adjoining a new row and then the remaining new column. Starting with , extend at a successor by for and for . Thus . At limits take compatible unions. The two new domain pieces are disjoint; the column is empty at the initial step . Each step enumerates consecutive ordinal intervals, proving bijectivity by transfinite induction. Finite stages have . Successor and limit cardinality arguments then give the square equality for well-orderable infinite cardinals without using that equality to justify the construction.

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