We have the following indirect implication of form equivalence classes:
			
| Implication | Reference | 
|---|---|
| 89 \(\Rightarrow\) 90 | The Axiom of Choice, Jech, 1973b, page 133 | 
| 90 \(\Rightarrow\) 91 | The Axiom of Choice, Jech, 1973b, page 133 | 
| 91 \(\Rightarrow\) 79 | clear | 
| 79 \(\Rightarrow\) 212 | clear | 
Here are the links and statements of the form equivalence classes referenced above:
| Howard-Rubin Number | Statement | 
|---|---|
| 89: | Antichain Principle: Every partially ordered set has a maximal antichain. Jech [1973b], p 133. | 
| 90: | \(LW\): Every linearly ordered set can be well ordered. Jech [1973b], p 133. | 
| 91: | \(PW\): The power set of a well ordered set can be well ordered. | 
| 79: | \({\Bbb R}\) can be well ordered. Hilbert [1900], p 263. | 
| 212: | \(C(2^{\aleph_{0}},\subseteq{\Bbb R})\): If \(R\) is a relation on \({\Bbb R}\) such that for all \(x\in{\Bbb R}\), there is a \(y\in{\Bbb R}\) such that \(x\mathrel R y\), then there is a function \(f: {\Bbb R} \rightarrow{\Bbb R}\) such that for all \(x\in{\Bbb R}\), \(x\mathrel R f(x)\). | 
Comment: