Algorithm 1.

IEPF(P, ϵ)

Input: P = {P1 … Pn}: a graphical representation of a TS as n points in ${\mathbb{R}}^2$; ϵ: a distance threshold.

Output: Sϵ(P): a subset of points of P that satisfies the distance criterion given by the threshold ϵ.

dmax ← 0

for i ← 2 to n − 1 do

$d\leftarrow \text{dist}(\overline{P_1{P}_n},P_i)$

if d > dmax then

dmax ← d

imax ← i

end if

end for

if dmax > ϵ then

Sϵ (P) ← IEPF(P1 … Pimax, ϵ) ⋃ IEPF(Pimax … Pn, ϵ)

else

Sϵ(P) ← P

end if