P-curve: An improved solution for the single-facility location problem in two regions with $\ell_{p}$- and $\ell_{q}$-norms
The distance between two points is provided by the length of their test connecting path. However, there is no unique way to attain this path in the space $R^2$, which is split by a straight line $L$ into two regions, $Ω_p$ and $Ω_q$, with $\ell_{p}$- and $\ell_q$-norms, respectively, where $1<p\leq q $ and $L\subsetΩ_q$. In this paper, given a point $P\in Ω_p$, the locus of points $Q\inΩ_p$, called $p$-curve, is found, such that there are two ways to attain the distance between $P$ and $Q$. For each $P\in Ω_p$, there are two $p$-curves which are two branches of two different $p$-parabola. These two branches split $Ω_p$ into three subregions using a three-link shortest path in two of these regions. The implicit equation of each $p$-parabola is given. Furthermore, by using the $p$-curve, an improved algorithm, called P-MFP, based on the MFP algorithm, is developed in order to solve the single-facility location problem in two regions with $\ell_{p}$ and $\ell_{q}$-norms. The results obtained with the new algorithm are better than those obtained with the MFP algorithm.ike subheadings, citations, or equations are permitted.