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IB DP Computer Science Study Notes

B.4.3 Natural Language Structures

To model communication effectively, it's essential to grasp the fundamental structures of natural language.

Lexical Categories

  • Nouns represent entities or concepts, such as "computer" or "algorithm".
  • Verbs signify actions or states, like "compute" or "exist".


  • Syntax governs how words combine to form valid sentences, following specific grammatical rules and structures.
  • Sentences are structured in phrases, each serving a syntactical purpose: noun phrases (NP), verb phrases (VP), and prepositional phrases (PP).


  • Semantics focuses on the meaning behind words and sentences.
  • This includes understanding denotations (direct meanings), connotations (implied meanings), and the role of context in interpreting sentences.

Human vs Machine Learning in Language

The acquisition and processing of language differ significantly between humans and machines.

Cognitive Learning in Humans

  • Humans learn language through a complex interplay of cognitive processes, including exposure, imitation, and reinforcement.
  • Cognitive learning encompasses both explicit instruction and implicit absorption of linguistic patterns.

Heuristics in Human Learning

  • Heuristics play a role in human language acquisition, guiding learners through general rules and patterns, which are often internalised through repeated exposure.

Probabilities in Machine Learning

  • Machines utilise statistical models to process language, often relying on algorithms that compute the probabilities of certain linguistic patterns occurring.

Differences in Approach

  • Human learning is adaptive and can handle ambiguities naturally, whereas machine learning requires extensive data and computational power to approach a similar level of linguistic understanding.

Machine Learning and NLP

Machine learning provides the backbone for NLP, enabling machines to process and generate human language.

Heuristic-Based Approaches

  • Initially, machines used heuristic-based approaches, relying on sets of rules crafted by linguists to parse and generate language.

Probabilistic Models

  • Probabilistic models, such as Hidden Markov Models (HMMs), improved NLP by considering the likelihood of sequences of words or phrases.

Supervised vs Unsupervised Learning

  • Supervised learning involves training algorithms on data that is tagged or labelled, like a corpus where sentences are annotated with their corresponding parts of speech.
  • Unsupervised learning algorithms, such as clustering and association, detect patterns and structures in unlabelled data.

Evolution of Machine Translators

Machine translation has developed from rudimentary systems to advanced models that can rival human translators in some contexts.

Early Machine Translators

  • The first machine translation systems were based on simple rule-based methods, often resulting in literal and awkward translations.

Statistical Machine Translation (SMT)

  • SMT marked a paradigm shift by using statistical algorithms to predict the best possible translation based on bilingual text data.

Neural Machine Translation (NMT)

  • NMT uses deep learning to create more accurate and contextually appropriate translations, often employing Recurrent Neural Networks (RNNs) and Long Short-Term Memory (LSTM) networks.

Advances in NLP

NLP has made leaps in understanding and generating human language, driven by advances in algorithms and computational power.

Pattern Recognition

  • Early NLP systems used pattern-matching techniques to identify linguistic structures, whereas contemporary models use complex algorithms to learn these patterns.

Contextual Understanding

  • Models like Bidirectional Encoder Representations from Transformers (BERT) and Generative Pre-trained Transformer 3 (GPT-3) have pushed the boundaries in understanding context and generating text that is indistinguishable from that written by humans.

Applications of NLP

  • NLP applications now extend to various domains such as sentiment analysis, chatbots, and automated summarization, each requiring a deep understanding of language nuances.

Implications for Communication Modelling

The synergy between NLP and communication modelling has far-reaching implications for technology and society.

Enhancing Human-Machine Interaction

  • Improved NLP models enhance the interface between humans and machines, making interactions more natural and intuitive.

Educational Applications

  • In educational settings, NLP systems can provide personalised learning experiences by understanding and responding to student queries.

Ethical Considerations

  • As machines become better at modelling language, ethical considerations regarding privacy, security, and the impact on human communication become increasingly important.


This comprehensive examination of natural language in communication modelling demonstrates the intricate relationship between language structures, learning processes, and computational methods, heralding a future where machines might understand and interact using natural language as proficiently as humans.


The development of modern machine translators has had a profound impact on the field of linguistics, particularly in the study of computational linguistics. It has propelled forward the understanding of language structure and processing, demonstrating that statistical and neural network-based approaches can effectively model language. This has challenged traditional linguistic theories that often emphasised rule-based understanding of language. Additionally, the vast amount of language data generated and required for training translators has contributed to the development of corpora linguistics, enhancing the empirical study of language.

The advancement of machine translators has significantly lowered the language barriers in global communication, enabling people to interact and exchange information across different languages with ease. It has revolutionised international business, travel, and diplomacy by providing instant translation services that are increasingly accurate and context-aware. Furthermore, the accessibility of online education and information has been greatly enhanced, as content can be readily translated into multiple languages, allowing for wider dissemination of knowledge and cultural exchange.

Heuristics are used in machine learning to provide a 'shortcut' in decision-making processes, allowing algorithms to make judgements without exhaustive computation. In NLP, heuristics can help to quickly approximate solutions for complex language problems. For example, a heuristic might be used to infer the meaning of a sentence based on keyword analysis or to prioritise certain rules of grammar when parsing sentences. The use of heuristics is particularly beneficial in cases where processing power is limited or when a quick response is more valuable than a perfectly accurate one.

Neural networks are inspired by the interconnected neuron structure of the human brain. They consist of layers of interconnected nodes (neurons) that process input data and generate output. This structure allows neural networks to learn complex patterns through training. In NLP, such networks can capture the intricacies of human language by recognising patterns in text data. The advantage of this biological mimicry is the ability of neural networks to handle vast amounts of data and learn from it, thus improving their language processing capabilities over time, similar to how humans learn and improve their language skills.

Denotation refers to the literal, dictionary meaning of a word, while connotation involves the additional meanings that a word suggests in particular contexts, including the emotional or cultural nuances. In NLP, distinguishing between denotation and connotation is crucial because it affects the system's ability to interpret and generate human-like language. For instance, understanding that 'home' denotes a place of residence and connotes warmth and security allows an NLP system to produce or interpret language that is more nuanced and contextually appropriate. This distinction helps in tasks like sentiment analysis, where the emotional tone of text is important.

Practice Questions

Describe the role of a fitness function in genetic algorithms and how it applies to a problem like the travelling salesman problem.

A fitness function in genetic algorithms is a particular type of objective function that evaluates how close a given solution is to achieving the set goals. In the context of the travelling salesman problem, the fitness function would measure the total distance travelled in a particular route. An excellent solution would be a route with the shortest possible distance, fulfilling the problem's aim of minimising travel cost. Therefore, the fitness function guides the selection process within the genetic algorithm, favouring solutions that offer shorter routes and thus, are more 'fit'.

Explain the difference between supervised and unsupervised learning in the context of neural networks and provide an example of each.

Supervised learning in neural networks involves training a model on a labelled dataset, which means that the input data is paired with correct output data. An example of supervised learning is a spam filter, which is trained to identify spam emails from non-spam by learning from a set of emails labelled as 'spam' or 'not spam'. Unsupervised learning, on the other hand, does not use labelled data. Instead, it identifies patterns and relationships within the data. An example is customer segmentation in marketing, where a model groups customers with similar buying patterns without prior labelling of the data.

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Written by: Alfie
Cambridge University - BA Maths

A Cambridge alumnus, Alfie is a qualified teacher, and specialises creating educational materials for Computer Science for high school students.

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