“…The local sensitivity of such systems has been analysed, e.g., in Fiacco (1983Fiacco ( , 1984 and Robinson (1987). Many authors have used bifurcation and singularity theory to investigate the local behaviour and persistence of minima at the singular points of this system, see, e.g., Bank, Guddat, Klatte, Kummer and Tammer (1983), Gfrerer, Guddat and Wacker (1983), Gfrerer, Guddat, Wacker and Zulehner (1985), Guddat, Guerra Vasquez and Jongen (1990), Guddat, Jongen, Kummer and Nozicka (1987), Twilt (1983, 1986), Jongen and Weber (1990), Kojima and Hirabayashi (1984) and Tiahrt (1987, 1990). Rakowska, Haftka and Watson (1991) discuss algorithms for tracking paths of optimal solutions.…”