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--- groimp-platform:xl-query [2025/01/10 11:41] – created gaetan
+++ groimp-platform:xl-query [2025/01/24 09:51] (current) – [Nested Transitive closures] Tim
@@ Line 39: / Line 39: @@
 |**Combined** |||
 | %%f:F, A +> f, A < f %% | {f1} | patterns combined by comma |
+====== Additional information ======
+===== Field based conditions=====
+{{:groimp-platform:parametric_example_graph_queries.png?direct&400 |}}
+|Query | Result | Description |
+| A(2,2.3)| a1  | all fields are defined |
+| A(2,)   | a1,a3,a4| only the first field is defined and considered |
+| A(2,x),(x>2) | a1,a3 | the first field is set, the second is a query variable used in a condition |
+| A(,x),(x>2) | a1,a2,a3 | the first field undefined, the second is a query variable used in a condition |
+| A(x,y),(x>y) | a4 | both fields are query variables used in the same condition |
+The condition part behind the comma can be replaced by any boolean condition, including predefined functions that return a boolean value.
+The query variables defined here can also be used in the production of the rewriting rule or in followup expressions of a lambda expression.
+===== Queries as query conditions =====
+As said above a query condition can be any boolean condition, this includes also queries and lambda expressions, as long as the return a boolean value for example the [[groimp-platform:xl-builtin-methods|Analytical Operator]] empty(), here used to find the last F of each branch and remove it using a [[:groimp-platform:xl-rules |SPO rule]].
+<code>
+[f:F,(empty((*f (-->)+ F*))) ==>>;]
+</code>
+Or a query as a part of a boolean condition, for example used with the count operator to get the order of an internode in a tree model:
+<code>
+(*f:F,(count((*f ((<)*<+)+F*))==0)*) //all F of order 0
+(*f:F,(count((*f ((<)*<+)+F*))==1)*) //all F of order 1
+</code>
+The inner query of this is explained below.
+===== Transitive closures =====
+As shown above transitive closure can be used to define a range of edges between two nodes, e.g. ''%% A (>)* B %%'' for all B with A successor of an A. This can be combined with other edges: ''%%  A (>)* +> B %%'' to show
+| query  | description |
+| ''%% A (>)+ B %%'' | All B's that have a A above connected only by successor edges |
+| ''%% A (>)* +> B %%'' | All B's that have a A above connected only by successor edges and one branch-edge directly before the B|
+| ''%% A ((>)* +>)+ B %%'' | All B's where the edge pattern of as many successors and one branch, comes at least once between the B and an A|
+| ''%% A (>)* +> (>)* B %%'' | As many sucessors followed by a branch followed by as many successors |
+| ''%% A (-->)* C (-->)* B %%''| All B' that have an ancestor of the type A and an ancestor of the type C with C between the A and the B |
+Using transitive closure it is possible to find the same node several times!!! for instance  in a graph
+%%Axiom ==> A A A B;%%
+the pattern (*A (>)* B*) would return B three times.