reserve i,j,k,n,m for Nat;
reserve p,q for Point of TOP-REAL 2;
reserve G for Go-board;
reserve C for Subset of TOP-REAL 2;

theorem :: JORDAN4:47
  for h being FinSequence of TOP-REAL 2 st i in dom h & j in dom h holds
  L~mid(h,i,j) c= L~h
proof
  let h be FinSequence of TOP-REAL 2;
  assume that
A1: i in dom h and
A2: j in dom h;
A3: i <= len h by A1,FINSEQ_3:25;
A4: j <= len h by A2,FINSEQ_3:25;
A5: 1 <= j by A2,FINSEQ_3:25;
  1 <= i by A1,FINSEQ_3:25;
  hence thesis by A3,A5,A4,JORDAN4:35;
end;
