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On Galilean connections and the first jet bundle

James Grant, Bradley Lackey (2012)

Open Mathematics

We see how the first jet bundle of curves into affine space can be realized as a homogeneous space of the Galilean group. Cartan connections with this model are precisely the geometric structure of second-order ordinary differential equations under time-preserving transformations - sometimes called KCC-theory. With certain regularity conditions, we show that any such Cartan connection induces “laboratory” coordinate systems, and the geodesic equations in this coordinates form a system of second-order...

On global transformations of functional-differential equations of the first order

Václav Tryhuk (2000)

Czechoslovak Mathematical Journal

The paper describes the general form of functional-differential equations of the first order with m ( m 1 ) delays which allows nontrivial global transformations consisting of a change of the independent variable and of a nonvanishing factor. A functional equation f ( t , u v , u 1 v 1 , ... , u m v m ) = f ( x , v , v 1 , ... , v m ) g ( t , x , u , u 1 , ... , u m ) u + h ( t , x , u , u 1 , ... , u m ) v for u 0 is solved on and a method of proof by J. Aczél is applied.

On global transformations of ordinary differential equations of the second order

Václav Tryhuk (2000)

Czechoslovak Mathematical Journal

The paper describes the general form of an ordinary differential equation of the second order which allows a nontrivial global transformation consisting of the change of the independent variable and of a nonvanishing factor. A result given by J. Aczél is generalized. A functional equation of the form f ( t , v y , w y + u v z ) = f ( x , y , z ) u 2 v + g ( t , x , u , v , w ) v z + h ( t , x , u , v , w ) y + 2 u w z is solved on for y 0 , v 0 .

On gradient at infinity of semialgebraic functions

Didier D'Acunto, Vincent Grandjean (2005)

Annales Polonici Mathematici

Let f: ℝⁿ → ℝ be a C² semialgebraic function and let c be an asymptotic critical value of f. We prove that there exists a smallest rational number ϱ c 1 such that |x|·|∇f| and | f ( x ) - c | ϱ c are separated at infinity. If c is a regular value and ϱ c < 1 , then f is a locally trivial fibration over c, and the trivialisation is realised by the flow of the gradient field of f.

On granular derivatives and the solution of a granular initial value problem

Ildar Batyrshin (2002)

International Journal of Applied Mathematics and Computer Science

Perceptions about function changes are represented by rules like “If X is SMALL then Y is QUICKLY INCREASING.” The consequent part of a rule describes a granule of directions of the function change when X is increasing on the fuzzy interval given in the antecedent part of the rule. Each rule defines a granular differential and a rule base defines a granular derivative. A reconstruction of a fuzzy function given by the granular derivative and the initial value given by the rule is similar to Euler’s...

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