Timeline for Cardinality: Why is there no "ℵ½"?
Current License: CC BY-SA 2.5
3 events
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| May 18, 2010 at 16:26 | comment | added | Tom Boardman | Indeed. But aleph_1 is omega_1 by definition- a set has cardinality aleph_1 if there exists a bijection between it and omega_1- as to whether that just consists of uncountable well ordered sets is a matter for AC. | |
| May 18, 2010 at 15:51 | comment | added | Gerald Edgar | You probably need AC to identify cardinals with ordinals. Without AC, perhaps not all cardinals are ordinals. | |
| May 18, 2010 at 15:01 | history | answered | Tom Boardman | CC BY-SA 2.5 |