Changes

Line 3,917: Line 3,917:  
\\[6pt]
 
\\[6pt]
 
& = &
 
& = &
\{ (x, y) \in L : x = u \}
+
\{ (u, y) \in L \}
 
\\[6pt]
 
\\[6pt]
 
& = &
 
& = &
Line 3,927: Line 3,927:  
\\[6pt]
 
\\[6pt]
 
& = &
 
& = &
\{ (x, y) \in L : y = v \}
+
\{ (x, v) \in L \}
 
\\[6pt]
 
\\[6pt]
 
& = &
 
& = &
 
\text{the set of all ordered pairs in}~ L ~\text{incident with}~ v \in Y.
 
\text{the set of all ordered pairs in}~ L ~\text{incident with}~ v \in Y.
 +
\end{array}</math>
 +
|}
 +
 +
The following definitions are also useful:
 +
 +
{| align="center" cellspacing="6" width="90%"
 +
|
 +
<math>\begin{array}{lll}
 +
u \cdot L
 +
& = &
 +
\operatorname{proj}_2 (u \star L)
 +
\\[6pt]
 +
& = &
 +
\{ y \in Y : (u, y) \in L \}
 +
\\[6pt]
 +
& = &
 +
\text{the elements of}~ Y ~\text{that are}~ L\text{-related to}~ u.
 +
\\[9pt]
 +
L \cdot v
 +
& = &
 +
\operatorname{proj}_1 (L \star v)
 +
\\[6pt]
 +
& = &
 +
\{ x \in X : (x, v) \in L \}
 +
\\[6pt]
 +
& = &
 +
\text{the elements of}~ X ~\text{that are}~ L\text{-related to}~ v.
 
\end{array}</math>
 
\end{array}</math>
 
|}
 
|}
12,080

edits