Base Concepts in Artificial Intelligence
Artificial Intelligence

Base Concepts in Artificial Intelligence

Mandi D 8 September 2023

Artificial intelligence incorporates a multifaceted collection of programming techniques, architectures, algorithms and methodologies. By combining strengths across this rich landscape of approaches, contemporary AI systems exhibit increasingly sophisticated capabilities. Here we delve deeper into the key concepts powering AI’s versatility and burgeoning practical impact.

Machine Learning

Machine learning provides the mathematical frameworks and programmatic tools that enable computers to learn from data and improve through experience rather than being explicitly programmed for every scenario. It represents a dominant approach underlying many AI achievements today.

Supervised Learning

In supervised learning, algorithms are trained on labeled datasets containing input examples mapped to known output labels. By learning correlations between inputs and outputs, models can predict the correct labels for new unseen inputs. Main techniques include:

  • Classification – Assign categorical labels to data points. Used for image recognition, document classification, spam detection, diagnostics and more. Algorithms include logistic regression, naive Bayes classifier, support vector machines, random forests, neural networks.
  • Regression – Predict continuous numeric values for data points like timestamps or housing prices. Techniques include linear regression, logistic regression, decision trees, support vector regression, and multivariate regression.
  • Structured learning – Output variables have temporal or spatial interdependence like sequences or graphs. Methods include hidden Markov models, conditional random fields, and graph neural networks.

Unsupervised Learning

In unsupervised learning, algorithms must find inherent hidden structure within unlabeled, uncategorized data. Key techniques include:

  • Clustering – Group data points by similarity, used for customer segmentation, social network analysis, bioinformatics, recommender systems. Algorithms include k-means, DBSCAN, hierarchical clustering, spectral clustering.
  • Dimensionality reduction – Simplify representations of data using feature selection or feature extraction. Helps visualize and compress high dimensional data while retaining most information. Methods include PCA, matrix factorization, autoencoders.
  • Density estimation – Estimate probability density functions modeling the distribution of data points. Used to generate new examples from the distribution. Techniques include kernel density estimation, Gaussian mixture models, variational autoencoders.

Semi-Supervised Learning

Semi-supervised learning combines a small labeled dataset with a larger unlabeled dataset during training. This can provide better performance by leveraging unlabeled data while requiring less labeling effort. Algorithms include self-training, generative models, graph-based techniques.

Reinforcement Learning

Reinforcement learning algorithms learn by interacting with dynamic environments, observing results of actions and optimizing behaviors to maximize cumulative rewards. Key concepts include:

  • Agent observes environment state, takes action, receives reward or penalty and adjusts strategy.
  • Markov decision processes formally model environments with states, actions, transition probabilities and rewards.
  • Algorithms like Q-learning and policy gradients steer agents toward optimal policies.

Used for game playing, robotics, resource management, control systems.

Neural Networks

Neural networks take inspiration from the parallel architecture of neurons in the human brain. These layers of simple computing units enable powerful statistical modeling and machine learning when networked in sufficient complexity.

Biological Basis

In the brain, networked biological neurons transmit electrochemical signals between input dendrites, through the cell body, along axons, across synapses to dendrites of subsequent neurons. Adjustable synaptic strengths enable learning across connections.

Artificial Neurons

Artificial neurons simplify this processing. Weighted input signals are summed and passed through an activation function to produce the neuron output. Common activation functions include sigmoid, ReLU, tanh. Adjusting synaptic weights lets networks learn complex relationships.

Network Architectures

Chaining many layers of neurons creates capable statistical models and learning systems:

  • Perceptrons – Simple feedforward networks, building blocks for multilayer networks.
  • Convolutional nets – Powerful for computer vision, apply sliding filters to recognize visual patterns and spatial hierarchies.
  • Recurrent nets – Feedback connections model temporal context, useful for speech, text, time series data.
  • Modularity – Conceptual modules encode specific capabilities, which can be composed into larger networks.

Representational Power

Given sufficient layers, neural networks can represent any continuous function allowing universal approximation capabilities. Deep networks exponentially expand modeling capacity over shallow ones.

Learning Process

Networks learn via backpropagation – errors are propagated backwards to adjust synaptic weights across many layers towards optimal values that minimize loss. This overcomes credit assignment challenges in multilayer networks.

Real-World Impact

When paired with increasing computing power and data, deep neural networks fueled AI breakthroughs in computer vision, speech recognition, machine translation, gaming and more in the 2010s. Neural networks underpin contemporary AI.

Natural Language Processing

Natural language processing (NLP) enables computers to analyze, process and generate human languages like English. NLP powers applications like virtual assistants, language translation, sentiment analysis and text summarization.

Text Analysis

Key techniques for extracting information from text:

  • Sentence segmentation – Identify sentence boundaries within text.
  • Word tokenization – Split sentences into words and punctuation.
  • Part-of-speech tagging – Label words with grammatical roles like noun, adjective, verb. Useful for parsing meaning.
  • Named entity recognition – Identify and classify entities within text into predefined types like people, organizations, locations.
  • Semantic analysis – Map text to known concepts and meanings. Disambiguate word senses based on context.

Machine Translation

Automatically translate text between human languages:

  • Rule-based – Manually defined translation rules and dictionaries.
  • Statistical – Train models on large bilingual corpora to learn probability of translations.
  • Neural networks – Sequence-to-sequence neural models represent entire sentences for translation.
  • Multilingual models – Single models translate between multiple language pairs.

Text Generation

Generate realistic text reflecting syntax and semantics of human languages:

  • Templates – Fill predefined text templates and patterns. Simple but limited flexibility.
  • Probabilistic methods – Sample words from learned language models capturing rules and regularities.
  • Planning – Construct sentences symbolically using lexicon and grammar constraints.
  • Neural networks – Generate text autoregressively with models like GPT-3.

Speech Processing

Transcribe speech audio into text and synthesize speech audio from text:

  • Speech recognition – Acoustic modeling analyzes audio signals. Language modeling ensures plausibility of transcribed text.
  • Speech synthesis – Text-to-speech (TTS) generates audio outputs from text. Uses waveform synthesis, concatenative TTS, neural TTS.
  • Speaker recognition – Identify speakers from vocal characteristics. Verifying identities or matching voices.

Dialog Systems

Interactive systems with conversational abilities for information retrieval, transactions, entertainment:

  • Task-oriented – Goal-driven dialog for reservations, customer service etc.
  • Non-task oriented – Open-ended conversation modeling personalities.
  • Architectures – Modular pipelines handling speech recognition, NLU, state tracking, response generation.

Computer Vision

Computer vision involves extracting useful information from visual inputs like images and videos. It enables capabilities like object recognition, scene understanding, image generation and facial analysis.

Image Analysis

Algorithms can localize, identify and understand objects within images:

  • Image classification – Label images based on their primary object or scene type.
  • Object detection – Detect instances of objects like pedestrians or vehicles, along with their locations using bounding boxes. Enables analyzing complex visual environments.
  • Image segmentation – Cluster image pixels belonging to the same object class. Allows separating foreground from background.
  • Activity recognition – Understand actions and behaviors of people and objects from video. Requires modeling motion and temporal dynamics.

Representation Learning

Neural networks excel at learning hierarchical representations:

  • Convolutional layers – Detect local combinations of edges, textures, parts that compose larger objects.
  • Embedding layers – Map images into vector space where similarity represents semantic closeness.
  • Transfer learning – Features learned on large datasets transfer well to new tasks with limited data.

Generative Modeling

Models can synthesize novel, realistic images and videos:

  • Generative adversarial networks (GANs) – Competing generator and discriminator networks enable high-quality image generation.
  • Variational autoencoders (VAEs) – Learn compressed latent representations from data and reconstruct inputs.
  • Autoregressive models – Sample pixels sequentially based on probabilities conditioned on previous pixels.
  • Applications – Image-to-image translation, in-painting missing regions, super-resolution, fashion design, virtual avatars.

Facial Analysis

Specialized techniques for analyzing human faces:

  • Detection and tracking – Locate faces within images and video.
  • Alignment – Register faces to reference frames adjusting for orientation and scale. Enables comparing facial features.
  • Recognition – Match faces to an identity database to authenticate users or identify people.
  • Emotion recognition – Classify facial expressions into basic emotional states.

Robotics

Robotics research aims to develop intelligent systems that sense, plan, act and learn to interact with the physical world. Integrating AI facilitates autonomous control.

Components

Robots comprise sensors, actuators and computational units:

  • Sensors – Cameras, LIDAR, ultrasonic, pressure provide environmental data.
  • Actuators – Motors, pistons, hydraulics, electromagnetic enable physical motion.
  • Controllers – Microcontrollers to low-level servos and high-level AI planning systems.

Control Systems

Software controls enable autonomy by directing actuators based on algorithms and sensor inputs:

  • Deliberative control – Create action plans based on models of environments using automated planning techniques.
  • Reactive control – Dynamically respond to sensor stimuli using rules, behaviors and reflexes.
  • Hybrid control – Layer deliberative planning with reactive skills.

Navigation and Mapping

Mobile robots like self-driving cars require spatial reasoning skills:

  • Path planning – Find obstacle-free paths to goal coordinates using search algorithms.
  • Simultaneous localization and mapping (SLAM) – Construct spatial maps of environments while localizing robot position.
  • Computer vision – Recognize landmarks and terrain from visual feeds.

Swarm Robotics

Coordinating robot collectives exhibiting emergent swarm intelligence:

  • Communication – Enable information sharing between robots via wireless networks.
  • Distributed control – Decentralized algorithms for task allocation, synchronization, movement.
  • Applications – Construction, collective transport, surveillance, search and rescue.

AI Integration

Artificial intelligence enhances robotic capabilities:

  • Reasoning and planning – Automated planning systems can synthesize complex behavior sequences.
  • Learning and adaptation – Improve control policies over time from environmental experience and human feedback.
  • Interaction – Natural language and computer vision facilitate working with people.

Together these foundational concepts empower artificial intelligence to assist, augment and automate tasks across practically every domain of life and work. Sustained progress in algorithms, data and computation portend even more capable AI applications ahead.