ρ ±

4 π 1 +

π 2 +

π 3 + π 4 +

4 π 1

π 2

π 3 π 4

4 π 1 +

16 ( π 1 + , π 1 + )

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π 2 +

4 ( π 2 + , π 1 + )

( π 2 + , π 2 + )

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π 3 + π 4 +

4 ( π 3 + , π 1 + ) π 4 +

( π 3 + , π 2 + ) π 4 +

( π 3 + , π 3 + ) 2 π 4 +

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4 π 1

16 ( π 1 , π 1 + )

4 ( π 1 , π 2 + )

4 ( π 1 , π 3 + ) π 4 +

16 ( π 1 , π 1 )

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π 2

4 ( π 2 , π 1 + )

( π 2 , π 2 + )

( π 2 , π 3 + ) π 4 +

4 ( π 2 , π 1 )

( π 2 , π 2 )

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π 3 π 4

4 ( π 3 , π 1 + ) π 4

( π 3 , π 2 + ) π 4

( π 3 , π 3 + ) π 4 0

4 ( π 3 , π 1 ) π 4

( π 3 , π 2 ) π 4

( π 3 , π 3 ) 2 π 4