关键词: 解, 先验界, 边值问题, 微分方程

Abstract:

x(4)=f(t,x,x′,x″,x) ,
boundary value condition
were considered and results were obtained, here the boundary value condition is one of the followings:
x(0)=A,x(1)=B,x″(0)=,x″(1)=,
x(0)=A,x(1)=B,x″(0)=,x(1)=,
x(0)=A,x(1)=B,x(0)=,x″(1)=,
x(0)=A,x′(1)=B,x″(0)=,x″(1)=,
x(0)=A,x′(1)=B,x″(0)=,x(1)=,
x(0)=A,x′(1)=B,x(0)=,x″(1)=,
x′(0)=A,x(1)=B,x″(0)=,x″(1)=,
x′(0)=A,x(1)=B,x″(0)=,x(1)=,
x′(0)=A,x(1)=B,x(0)=,x″(1)=.

These results were given to assume that the function f(t,x,y,p,r) satisfies the following condition. There are pairs (four or eight) of suitable constants such that f(t,x,y,p,r) does not change sign on sets of the form ［0,1］×Dx×Dy×Dp×I, where Dx,　Dy,　Dp are closed bounded intervals, I is a closed set in R and bounded by some pairs of constants, mentioned above.

Key words: boundary value problem, differential equation, solution, prior estimates