> ## Documentation Index > Fetch the complete documentation index at: https://docs.abbyy.com/llms.txt > Use this file to discover all available pages before exploring further. # Hypothesis tree > How the Extraction Rules activity builds a hypothesis tree, evaluates paths by multiplying quality values, and selects the best-rated path through the tree. When matching each Extraction Rules activity, the program sequentially builds hypotheses for all created elements. Element hypotheses are formulated sequentially (from the first element in the tree to the last). A hypothesis tree is then created using the formulated hypotheses. If the variant is matched successfully, the hypothesis tree is displayed in the **Tree of Hypotheses** pane: Hypothesis Tree Example If several variants have been matched, only the hypothesis tree of the variant matched first is displayed. If the activity could not be matched, the hypothesis tree for the first version is displayed. The program uses the hypothesis tree to select the best path, i.e. the best-rated path to the formulated hypothesis for the last element in the tree. Paths are evaluated by multiplying the quality values of all hypotheses of elements along the path. The location of the activity blocks is calculated using the hypotheses formulated for elements in the best path of a specific hypothesis tree. ## View element hypotheses To view element hypotheses for a group element: Click a hypothesis in the **Tree of Hypotheses** pane. Press **Enter** or use the **Show Details** command in the context menu. To navigate back by one level, use the **Go One Level Up** command in the context menu. ## Understand the hypothesis tree The left column of the hypothesis tree lists the elements of nesting level 1 in the same order as they are described in the element tree. The right column contains special icons representing hypotheses for that particular element. Formulated hypotheses are connected by lines that demonstrate the order of their formulation. Best path hypotheses are connected using green lines, while all other lines are gray. ## Hypothesis icons | Icon | Description | | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Best path | A hypothesis from the best path. | | Non-best path | A hypothesis not from the best path. | | Best path null | A null hypothesis from the best path. | | Non-best path null | A null hypothesis not from the best path. | | Incomplete chain | An incomplete chain of hypotheses for a Group element (Group, Repeating Group, Header, Footer). You can view an incomplete chain of hypotheses to locate a non-detected element. | | Best path+ Non-best+ Null best+ Null non-best+ | The branch of the element displays the hypothesis from the best path. To view all the hypotheses, press "+" or select **Expand Active** in the shortcut menu. | | Best path- Non-best- Null best- Null non-best- | Displays all the hypotheses in the branch of the element. To hide the hypotheses which are not from the best path, press "-" or select **Collapse Active** in the shortcut menu. | | Best end Non-best end Null best end Null non-best end Red striked | The sub-branch of hypotheses for the element was discontinued at this point. |