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 | | http://functions.wolfram.com/01.31.16.0004.01 | 
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 | | ProductLog[x] + ProductLog[y] == 
  ProductLog[x y (1/ProductLog[x] + 1/ProductLog[y])] /; x > 0 || y > 0 | 
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 | | Cell[BoxData[RowBox[List[RowBox[List[RowBox[List[RowBox[List["ProductLog", "[", "x", "]"]], "+", RowBox[List["ProductLog", "[", "y", "]"]]]], "\[Equal]", RowBox[List["ProductLog", "[", RowBox[List["x", " ", "y", " ", RowBox[List["(", RowBox[List[FractionBox["1", RowBox[List["ProductLog", "[", "x", "]"]]], "+", FractionBox["1", RowBox[List["ProductLog", "[", "y", "]"]]]]], ")"]]]], "]"]]]], "/;", RowBox[List[RowBox[List["x", ">", "0"]], "\[Or]", RowBox[List["y", ">", "0"]]]]]]]] | 
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   <math xmlns='http://www.w3.org/1998/Math/MathML' mathematica:form='TraditionalForm' xmlns:mathematica='http://www.wolfram.com/XML/'>  <semantics>  <mrow>  <mrow>  <mrow>  <mrow>  <mi> W </mi>  <mo> ⁡ </mo>  <mo> ( </mo>  <mi> x </mi>  <mo> ) </mo>  </mrow>  <mo> + </mo>  <mrow>  <mi> W </mi>  <mo> ⁡ </mo>  <mo> ( </mo>  <mi> y </mi>  <mo> ) </mo>  </mrow>  </mrow>  <mo> ⩵ </mo>  <mrow>  <mi> W </mi>  <mo> ⁡ </mo>  <mo> ( </mo>  <mrow>  <mi> x </mi>  <mo> ⁢ </mo>  <mi> y </mi>  <mo> ⁢ </mo>  <mrow>  <mo> ( </mo>  <mrow>  <mfrac>  <mn> 1 </mn>  <mrow>  <mi> W </mi>  <mo> ⁡ </mo>  <mo> ( </mo>  <mi> x </mi>  <mo> ) </mo>  </mrow>  </mfrac>  <mo> + </mo>  <mfrac>  <mn> 1 </mn>  <mrow>  <mi> W </mi>  <mo> ⁡ </mo>  <mo> ( </mo>  <mi> y </mi>  <mo> ) </mo>  </mrow>  </mfrac>  </mrow>  <mo> ) </mo>  </mrow>  </mrow>  <mo> ) </mo>  </mrow>  </mrow>  <mo> /; </mo>  <mrow>  <mrow>  <mi> x </mi>  <mo> > </mo>  <mn> 0 </mn>  </mrow>  <mo> ∨ </mo>  <mrow>  <mi> y </mi>  <mo> > </mo>  <mn> 0 </mn>  </mrow>  </mrow>  </mrow>  <annotation-xml encoding='MathML-Content'>  <apply>  <ci> Condition </ci>  <apply>  <eq />  <apply>  <plus />  <apply>  <ci> W </ci>  <ci> x </ci>  </apply>  <apply>  <ci> W </ci>  <ci> y </ci>  </apply>  </apply>  <apply>  <ci> W </ci>  <apply>  <times />  <ci> x </ci>  <ci> y </ci>  <apply>  <plus />  <apply>  <times />  <cn type='integer'> 1 </cn>  <apply>  <power />  <apply>  <ci> W </ci>  <ci> x </ci>  </apply>  <cn type='integer'> -1 </cn>  </apply>  </apply>  <apply>  <times />  <cn type='integer'> 1 </cn>  <apply>  <power />  <apply>  <ci> W </ci>  <ci> y </ci>  </apply>  <cn type='integer'> -1 </cn>  </apply>  </apply>  </apply>  </apply>  </apply>  </apply>  <apply>  <or />  <apply>  <gt />  <ci> x </ci>  <cn type='integer'> 0 </cn>  </apply>  <apply>  <gt />  <ci> y </ci>  <cn type='integer'> 0 </cn>  </apply>  </apply>  </apply>  </annotation-xml>  </semantics>  </math> 
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 | | Cell[BoxData[RowBox[List[RowBox[List["HoldPattern", "[", RowBox[List[RowBox[List["ProductLog", "[", "x_", "]"]], "+", RowBox[List["ProductLog", "[", "y_", "]"]]]], "]"]], "\[RuleDelayed]", RowBox[List[RowBox[List["ProductLog", "[", RowBox[List["x", " ", "y", " ", RowBox[List["(", RowBox[List[FractionBox["1", RowBox[List["ProductLog", "[", "x", "]"]]], "+", FractionBox["1", RowBox[List["ProductLog", "[", "y", "]"]]]]], ")"]]]], "]"]], "/;", RowBox[List[RowBox[List["x", ">", "0"]], "||", RowBox[List["y", ">", "0"]]]]]]]]]] | 
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 | | Date Added to functions.wolfram.com (modification date) | 
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