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<br>
 
<br>
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==Relations==
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==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.
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\end{array}</math>
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|}
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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:
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{| align="center" cellspacing="6" width="90%"
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|
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<math>\begin{array}{lll}
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f ~\text{is surjective}
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& \iff &
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f ~\text{is total at}~ Y.
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\\[6pt]
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f ~\text{is injective}
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& \iff &
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f ~\text{is tubular at}~ Y.
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\\[6pt]
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f ~\text{is bijective}
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& \iff &
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f ~\text{is}~ 1\text{-regular at}~ y.
 
\end{array}</math>
 
\end{array}</math>
 
|}
 
|}
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