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A solution to the automated generalisation of one particular class of geographical objects is proposed. Those objects are area patches distributed over a twodimensional space. They are assumed to be semantically identical; hence the competition for space occurs on the basis of geometric considerations only. The solution proposed is algorithmic, stepwise and works for vector data only. The steps include data preprocessing, area expansion and contraction, elimination, reselection, aggregation, displacement, integrity check, smoothing and reduction. Among the generalisation rules which were applied are: (1) emphasis on largerpatches at the expense of smaller ones, (2) preservation of the overall figure/group relationship, (3) partial topological integrity, and (4) differential displacement according to patch area. Results are discussed within the wider framework of topographic map generalisation where diversified objects must be simultaneously generalised.

Background: The application of esophagojejunostomy has certain difficulties in totally laparoscopic total gastrectomy (TLTG). This is due to the higher requirement for surgical techniques and the lack of any unified standards. This study aim to explore the practicability and safety of intracorporeal overlap and intracorporeal hand-sewn anastomosis compared with extracorporeal anastomosis. Methods:The clinical pathological data of 56 patients who underwent TLTG from March 2016 to Decemeber 2020 in the Harbin Medical University Cancer Hospital were retrospectively analyzed. According to the method of anastomosis, the patients were divided into the overlap (n=36) and the hand-sewn anastomosis (n=20). Patients who receive laparoscopic-assisted total gastrectomy (LATG; n=74) formed the control group.The basic clinical data, and intraoperative and postoperative results of the patients were assessed.Results: Compared with the control group, the overlap anastomosis and hand-sewn anastomosis groups showed no significant differences in clinicopathological data and short-term postoperative recovery. There were no significant differences between the overlap and the control group in operation time nor anastomosis time. However, the anastomosis time of the hand-sewn anastomosis group was significantly prolonged compared to the control group (53.20±14.14 vs. 43.01±12.53 minutes, P=0.002). Compared with the control group, the operation cost was significantly higher in the overlap group (CNY 81,300±6,100 vs. CNY 76,600±6,800, P=0.001), but significantly lower in the hand-sewn anastomosis group (CNY 71,900±1,700 vs. CNY 76,600±6,800, P=0.003). Early postoperative complications occurred in 5 cases (13.9%) in the overlap group, 3 cases (15.0%) in the hand-sewn anastomosis group, and 11 cases (14.9%) in the control group. There were 3 cases (8.3%) of postoperative anastomotic-related complications in the overlap group. No anastomotic-related complications were observed in the hand-sewn anastomosis group. Conclusions:The overlap anastomosis and hand-sewn anastomosis are practical and safe. Furthermore, the overlap anastomosis may be more suitable for patients with lower cardia and fundic lesions. The hand-sewn method has a wider range of indications pending advanced surgical skills, and is an effective supplementary technique for instrument anastomosis.

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