... conditions h < /b> (0) = h < /b> ( T )=0.Inthestandard theory< /b> ,wecallconjugatetimet a0<t≤ T suchthatthereexists anon trivial solution h < /b> of Dh =0,with h < /b> (0) = h < /b> ( t )=0.And wehave: 3Control < /b> of Mechanical ... 0:hyperboliccasec. λ+< 0, λ−> 0:ellipticcase.We have the following:Proposition3.16. Let z0be afoldpoint, thenthereexists aneighborhood Vof z0such that:1 . In thehyperbolic ... t<t1 c,the firstconjugate time,the referenceextremal canbeimbedded in the centralfield F whichforms,for t>0atubularneighborhood,onwhichthe extremalsarenot overlapping. We haveProposition...