**Learn the Basics** ||
`Quick Start <Quick-Start.html>`_ ||
`Dataset & Data Structure <Datasets.html>`_ ||
`Learning Part <Learning.html>`_ ||
`Reasoning Part <Reasoning.html>`_ ||
`Evaluation Metrics <Evaluation.html>`_ ||
`Bridge <Bridge.html>`_ 

Learn the Basics
================

Modules in ABLkit
----------------------

ABLkit is an efficient toolkit for `Abductive Learning <../Overview/Abductive-Learning.html>`_ (ABL), 
a paradigm which integrates machine learning and logical reasoning in a balanced-loop.
ABLkit comprises three primary parts: **Data**, **Learning**, and
**Reasoning**, corresponding to the three pivotal components of current
AI: data, models, and knowledge. Below is an overview of the ABLkit.

.. image:: ../_static/img/ABLkit.png

**Data** part efficiently manages data storage, operations, and evaluations.
It includes the ``ListData`` class, which defines the data structures used in
ABLkit, and comprises common data operations like insertion, deletion, 
retrieval, slicing, etc. Additionally, it contains a series of evaluation metrics 
such as ``SymbolAccuracy`` and ``ReasoningMetric`` (both specialized metrics 
inherited from the ``BaseMetric`` class), for evaluating performance from a 
data perspective.

:blue-bold:`Learning` part focuses on creating, training, and utilizing 
machine learning models. The ``ABLModel`` class is the 
central class that encapsulates the machine learning model. This class is
compatible with various frameworks, including those based on scikit-learn
or PyTorch neural networks constructed by the ``BasicNN`` class.

:green-bold:`Reasoning` part concentrates on constructing domain knowledge and 
performing reasoning. The ``KBBase`` class allows users to customize a 
domain knowledge base. For diverse types of knowledge, we also offer
implementations like ``GroundKB`` and ``PrologKB`` (both inherited 
from the ``KBBase`` class). The latter, for instance, imports
knowledge bases via Prolog files. Upon building the knowledge base, 
the ``Reasoner`` class is responsible for minimizing the inconsistency
between the knowledge base and data.

The integration of these three parts is achieved through the
:yellow-bold:`Bridge` part, which features the ``SimpleBridge`` class (derived 
from the ``BaseBridge`` class). The Bridge part synthesizes data, 
learning, and reasoning, facilitating the training and testing 
of the entire ABL framework.

Use ABLkit Step by Step
----------------------------

In a typical ABL process, as illustrated below, 
data inputs are first predicted by the learning model ``ABLModel.predict``, and the outcomes are pseudo-labels.
These labels then pass through deductive reasoning of the domain knowledge base ``KBBase.logic_forward``
to obtain the reasoning result. During training, 
alongside the aforementioned forward flow (i.e., prediction --> deduction reasoning), 
there also exists a reverse flow, which starts from the reasoning result and 
involves abductive reasoning ``KBBase.abduce_candidates`` to generate possible revised pseudo-labels. 
Subsequently, these pseudo-labels are processed to minimize inconsistencies with the learning part.
They in turn revise the outcomes of the learning model, which are then
fed back for further training ``ABLModel.train``.  

.. image:: ../_static/img/usage.png

To implement this process, the following five steps are necessary:

1. Prepare **datasets**

    Prepare the data's input, ground truth for pseudo-labels (optional), and ground truth for reasoning results.

2.  :blue:`Build the` :blue-bold:`learning` :blue:`part`

    Build a machine learning base model that can predict inputs to pseudo-labels. 
    Then, use ``ABLModel`` to encapsulate the base model.

3. :green:`Build the` :green-bold:`reasoning` :green:`part`

    Define a knowledge base by building a subclass of ``KBBase``, specifying how to 
    process pseudo-labels to reasoning results.
    Also, create a ``Reasoner`` for minimizing inconsistencies 
    between the knowledge base and data.

4. Define evaluation metrics

    Define the metrics by building a subclass of ``BaseMetric``. The metrics will 
    specify how to measure performance during the training and testing of the ABL framework.

5. :yellow-bold:`Bridge` :yellow:`learning and reasoning`

    Use ``SimpleBridge`` to bridge the learning and reasoning part
    for integrated training and testing.