@techreport{R-86-41, TITLE = {On Recognizing Polygons, or how to Eavesdrop}, AUTHOR = {James A. Dean and Andrzej Lingas and J{\"o}rg-R. Sack }, YEAR = {1986}, NUMBER = {R-86-41}, INSTITUTION = ida, ADDRESS = idaaddr, ABSTRACTURL = {/publications/cgi-bin/tr-fetch.pl?r-86-41+abstr}, ABSTRACT = {A new class of so called pseudo star-shaped polygons is introduced. A polygon is pseudo star-shaped if there is a point from which we can see/eavesdrop its whole interior provided that it is possible to see/hear through its single edges. The class of pseudo star-shaped polygons generalizes and unifies the well known classes of convex, monotone and pseudo star-shaped polygons. We give algorithms for testing whether a polygon is pseudo star-shaped from a given point in linear time, and for constructing all regions from which the polygon is pseudo star-shaped in quadratic time. Also, we show that many standard computational geometry problems can be solved efficiently for pseudo star-shaped polygons.}, IDANR = {LiTH-IDA-R-86-41}, NOTE = {Also in Proc of the Allerton Conference on Communication, Control, and Computing, Urbana, Illinois, 1986}