Talk:Formally real field
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[edit] Equivalence of the definitions
The text says: The equivalence of the first two properties is easy, and the third property easily implies the first two, but it is not easy to show either of the first two properties implies the third (that is, it is not evident how the assumption that a sum of squares being 0 forces each square to be 0 actually implies F has some ordering as a field)..
What is the meaning of not easy? I can imagine that it would require the axiom of choice; if so, this should be mentioned in the text. Albmont 17:35, 26 March 2007 (UTC)
