{"id":12626,"date":"2021-11-14T20:17:35","date_gmt":"2021-11-15T01:17:35","guid":{"rendered":"https:\/\/carleton.ca\/scs\/?page_id=12626"},"modified":"2026-06-02T14:59:26","modified_gmt":"2026-06-02T18:59:26","slug":"tr-117-recognizing-polygons-or-how-to-spy","status":"publish","type":"page","link":"https:\/\/carleton.ca\/scs\/research\/scs-technical-reports\/technical-reports-1987\/tr-117-recognizing-polygons-or-how-to-spy\/","title":{"rendered":"TR-117: Recognizing Polygons, or How to Spy"},"content":{"rendered":"\n<section class=\"w-screen px-6 cu-section cu-section--white ml-offset-center md:px-8 lg:px-14\">\n    <div class=\"space-y-6 cu-max-w-child-5xl  md:space-y-10 cu-prose-first-last\">\n\n            <div class=\"cu-textmedia flex flex-col lg:flex-row mx-auto gap-6 md:gap-10 my-6 md:my-12 first:mt-0 max-w-5xl\">\n        <div class=\"justify-start cu-textmedia-content cu-prose-first-last\" style=\"flex: 0 0 100%;\">\n            <header class=\"font-light prose-xl cu-pageheader md:prose-2xl cu-component-updated cu-prose-first-last\">\n                                    <h1 class=\"cu-prose-first-last font-semibold !mt-2 mb-4 md:mb-6 relative after:absolute after:h-px after:bottom-0 after:bg-cu-red after:left-px text-3xl md:text-4xl lg:text-5xl lg:leading-[3.5rem] pb-5 after:w-10 text-cu-black-700 not-prose\">\n                        TR-117: Recognizing Polygons, or How to Spy\n                    <\/h1>\n                \n                                \n                            <\/header>\n\n                    <\/div>\n\n            <\/div>\n\n    <\/div>\n<\/section>\n\n<p>Carleton University<br>\n<a href=\"https:\/\/carleton.ca\/scs\/research\/scs-technical-reports\/technical-reports-1987\/\">Technical Report<\/a> <strong>TR-117<\/strong><br>\nAugust 1987<\/p>\n\n\n\n<h2 id=\"recognizing-polygons-or-how-to-spy\" class=\"wp-block-heading tr_t1\">Recognizing Polygons, or How to Spy<\/h2>\n\n\n\n<div class=\"tr_t3\">\n<div class=\"tr_t3\">James A. Dean, Andrzej Lingas, J\u00f6rg-R\u00fcdiger Sack<\/div>\n<\/div>\n\n\n\n<div>\n<h3>Abstract<\/h3>\n<p>A new class of so-called pseudo-star-shaped polygons is introduced. A polygon is pseudo-star-shaped if there exists a point from which the whole interior of the polygon can be seen, provided it is possible to see through single edges. We show that the class of pseudo-star-shaped polygons unifies and generalizes 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. We show the latter algorithm to be worst-case optimal. Also, we give efficient algorithms solving standard geometrical problems such as point-location and triangulation for pseudo-star-shaped polygons.<\/p>\n<\/div>\n\n\n\n<p><a href=\"https:\/\/carleton.ca\/scs\/wp-content\/uploads\/sites\/260\/tr-117.pdf\">TR-117.pdf<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Carleton University Technical Report TR-117 August 1987 Recognizing Polygons, or How to Spy James A. Dean, Andrzej Lingas, J\u00f6rg-R\u00fcdiger Sack Abstract A new class of so-called pseudo-star-shaped polygons is introduced. A polygon is pseudo-star-shaped if there exists a point from which the whole interior of the polygon can be seen, provided it is possible to [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":11827,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"_cu_dining_location_slug":"","footnotes":"","_links_to":"","_links_to_target":""},"cu_page_type":[],"class_list":["post-12626","page","type-page","status-publish","hentry"],"acf":{"cu_post_thumbnail":false},"_links":{"self":[{"href":"https:\/\/carleton.ca\/scs\/wp-json\/wp\/v2\/pages\/12626","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/carleton.ca\/scs\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/carleton.ca\/scs\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/carleton.ca\/scs\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/carleton.ca\/scs\/wp-json\/wp\/v2\/comments?post=12626"}],"version-history":[{"count":2,"href":"https:\/\/carleton.ca\/scs\/wp-json\/wp\/v2\/pages\/12626\/revisions"}],"predecessor-version":[{"id":12628,"href":"https:\/\/carleton.ca\/scs\/wp-json\/wp\/v2\/pages\/12626\/revisions\/12628"}],"up":[{"embeddable":true,"href":"https:\/\/carleton.ca\/scs\/wp-json\/wp\/v2\/pages\/11827"}],"wp:attachment":[{"href":"https:\/\/carleton.ca\/scs\/wp-json\/wp\/v2\/media?parent=12626"}],"wp:term":[{"taxonomy":"cu_page_type","embeddable":true,"href":"https:\/\/carleton.ca\/scs\/wp-json\/wp\/v2\/cu_page_type?post=12626"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}