Differences

This shows you the differences between two versions of the page.

--- tutorial:polytope_semantics [2011/11/23 17:53] – [Special Cases] joswig
+++ tutorial:polytope_semantics [2017/03/29 14:04] – [Special Cases] hnagel
@@ Line 10: / Line 10: @@
 If a user asks for a property which cannot be derived this property is set to undef.  This occurs, e.g., if one asks for the ''VERTICES'' of a combinatorially defined polytope.
-For instance we have four possibilities which can occur for ''VERTICES''. The property
-  * does not exist (it is not listed in ''list_properties''): This basically means that the property is not derived/calculated, yet.
-  * exists and is set to ''undef'': Polymake is not able to derive this property with the given properties. The polytope might be empty or not.
-  * exists and is empty: So the polytope is empty.
-  * exists and is neither set to ''undef'' nor is empty: Our polytope is not empty and the property returns what you expect.
 ===== Objects of type ''Polytope'' =====
@@ Line 54: / Line 48: @@
 Such a polytope is both simple and simplicial, i.e. it is a simplex.
+=== Zero-dimensional fans ===
+A zero-dimensional fan can e.g. be defined via <code>$f=new PolyhedralFan(RAYS=>[], MAXIMAL_CONES=>[[]]);</code>
+==== Summing Up ====
+For instance we have four possibilities which can occur for ''VERTICES''. The property
+  * does not exist (it is not listed in ''list_properties''): This basically means that the property is not derived/calculated, yet.
+  * exists and is set to ''undef'': Polymake is not able to derive this property with the given properties. The polytope may be empty or not.
+  * exists and is empty: So the polytope is empty.
+  * exists and is neither set to ''undef'' nor is empty: Our polytope is not empty and the property returns what you expect.