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--- user_guide:extend:rules [2019/01/25 16:02] – ↷ Page moved from reference:rules to user_guide:extend:rules oroehrig
+++ user_guide:extend:rules [2021/01/12 15:38] (current) – external edit 127.0.0.1
@@ Line 32: / Line 32: @@
 === Labels ===
-Labels allow to control the choice of rules by the scheduler via [[:general#preferences|preference lists]] manipulated by the user.  Usually, rules with similar functionality are assigned labels with common tail part and different first limbs.  For example, different rules solving LP with the simplex method are labeled with ''cdd.simplex'', ''lrs.simplex'', etc.  After the user has issued a command ''%%prefer "cdd";%%'' the rule with ''lrs'' label is not considered by the scheduler until the ''cdd'' rule has failed on the object being processed.  In the absence of active preference lists, labeled rules are treated the same way as unlabeled ones.
+Labels allow to control the choice of rules by the scheduler via [[:user_guide:howto:shell_custom#preferences|preference lists]] manipulated by the user.  Usually, rules with similar functionality are assigned labels with common tail part and different first limbs.  For example, different rules solving LP with the simplex method are labeled with ''cdd.simplex'', ''lrs.simplex'', etc.  After the user has issued a command ''%%prefer "cdd";%%'' the rule with ''lrs'' label is not considered by the scheduler until the ''cdd'' rule has failed on the object being processed.  In the absence of active preference lists, labeled rules are treated the same way as unlabeled ones.
 Besides this, labels are involved in the overriding mechanism, and, finally, there are some special labels completely changing the semantics of the rule.  Both are described further on this page.
@@ Line 167: / Line 167: @@
   rule nonexistent : CYCLES : VertexPerm.CYCLES, VertexPerm.PERMUTATION;
 indicates that property CYCLES is dependent on the vertex order, and if some other rule (declared as possibly triggering VertexPerm) creates CYCLES while the object already contains other properties depending on the vertex order, it will be completely in vain, because there is no way to rearrange the CYCLES such that they fit the original vertex order.  (Actually, the CYCLES could easily be rearranged, but for some political reasons this has not been implemented yet.)