MyWikiBiz, Author Your Legacy — Friday December 19, 2025
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, 16:08, 16 November 2012
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| | <br> | | <br> |
| | | | |
| − | ==Relations== | + | ==Relations In General== |
| | | | |
| | Next let's re-examine the ''numerical incidence properties'' of relations, concentrating on the definitions of the assorted regularity conditions. | | Next let's re-examine the ''numerical incidence properties'' of relations, concentrating on the definitions of the assorted regularity conditions. |
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| | & \iff & | | & \iff & |
| | P ~\text{is}~ 1\text{-regular at}~ Y. | | P ~\text{is}~ 1\text{-regular at}~ Y. |
| | + | \end{array}</math> |
| | + | |} |
| | + | |
| | + | In the case of a 2-adic relation <math>F \subseteq X \times Y</math> that has the qualifications of a function <math>f : X \to Y,</math> there are a number of further differentia that arise: |
| | + | |
| | + | {| align="center" cellspacing="6" width="90%" |
| | + | | |
| | + | <math>\begin{array}{lll} |
| | + | f ~\text{is surjective} |
| | + | & \iff & |
| | + | f ~\text{is total at}~ Y. |
| | + | \\[6pt] |
| | + | f ~\text{is injective} |
| | + | & \iff & |
| | + | f ~\text{is tubular at}~ Y. |
| | + | \\[6pt] |
| | + | f ~\text{is bijective} |
| | + | & \iff & |
| | + | f ~\text{is}~ 1\text{-regular at}~ y. |
| | \end{array}</math> | | \end{array}</math> |
| | |} | | |} |