Reducing the number of fitness evaluations in graph genetic programming using a canonical graph indexed database.

In this paper we describe the genetic programming system GGP operating on graphs and introduce the notion of graph isomorphisms to explain how they influence the dynamics of GP. It is shown empirically how fitness databases can improve the performance of GP and how mapping graphs to a canonical form can increase these improvements by saving considerable evaluation time.

EUS-cholangio-drainage of the bile duct: report of 4 cases.

BACKGROUND: Endoscopic retrograde cholangiography with stent insertion is an established procedure for palliation of patients with malignant pancreaticobiliary strictures. In some patients, however, placement of a stent by means of a duodenoscope is not possible. Percutaneous transhepatic biliary drainage is an alternative method that has a complication rate of up to 15%. Four cases of successful EUS-guided-cholangio-drainage are presented in which the major papilla could not be cannulated at endoscopic retrograde cholangiography. METHODS: For puncture of the intrahepatic or extrahepatic bile duct, a modification of the one-step technique for the drainage of pancreatic pseudocysts was used. RESULTS: Stent insertion was successful in 3 of the 4 patients. In these 3 patients cholestasis resolved promptly. CONCLUSIONS: EUS-guided cholangio-drainage is a potential alternative to percutaneous transhepatic biliary drainage and endoscopic retrograde cholangiography in the therapy of malignant pancreaticobiliary strictures, especially in patients who have undergone gastrectomy or partial gastrectomy with Billroth II reconstruction.