... following scheme. Exchange π1 and 1 and then sort π2, ,πp1into ascending order. Next exchange πp1 +1 and the minimumof πp1 +1 , ,πn and then sort πp1 +2 , ,πp2into ascending order. ... potentialU(z)=z + tz2.Settingt = −ω2, and making a change of gaugeφ(z)=exp(ωz)ψ(z)transforms (4.4) intoz2ψ(z )+( 1− ν)zψ(z )+2 ωz2ψ(z)+z (ω(1 −ν )+1 )ψ(z)=0.Dividing through by z and settingγ ... letsj= p1 + + pj,j=1, ,ldenote the jthleft partial sum and set|p| = sl= p1 + + pl.Let us also define the following abbreviations:sp=l−1j=1sj,ap=l−1j=1asjsj+1Proposition...