Sofia University "St. Kliment Ohridski" Faculty of Mathematics and Informatics

Intelligent Systems / Artificial Intelligence

course @ Sofia University

Lab notes by Elitsa Yotkova and Kristina Kalemdzhieva

Labs

TopicDescriptionNotesQuizSlides
00Introduction Who we are and a map of the course: search, machine learning and language models Learn → Quiz → Coming soon
01Uninformed Search Basic definitions, state spaces, and blind search strategies (BFS, DFS, UCS, IDS) Learn → Quiz → Present →
02Informed Search Heuristic functions, greedy search, A* algorithm, and optimization techniques Learn → Quiz → Present →
03Constraint Satisfaction CSP fundamentals, backtracking, arc consistency (AC-3), and min-conflicts heuristics Learn → Quiz → Present →
04Genetic Algorithms Evolutionary search, selection mechanisms, crossover, mutation, and metaheuristic optimization Learn → Quiz → Present →
05Games Adversarial search, game trees, minimax, and alpha-beta pruning Learn → Quiz → Coming soon
06Introduction to ML Core concepts, bias and variance, regression and classification, KNN, SVM, Naive Bayes, decision trees, and K-Means Learn → Quiz → Coming soon
6.5Linear & Logistic Regression Cost function, gradient descent and the closed form, R² and RMSE, logit and sigmoid, cross-entropy, one-vs-rest and softmax Learn → Quiz → Coming soon
07K-Nearest Neighbours Global vs local, instance-based vs model-based and lazy vs eager learning, distance metrics, choosing K, KNN classification and regression Learn → Quiz → Coming soon
08Naive Bayes Classifier Bayes' theorem, conditional independence, spam filtering, the zero-probability problem and Laplace smoothing, Gaussian Naive Bayes Learn → Quiz → Coming soon
09Decision Trees Classification and regression trees, recursive construction, entropy as expected surprise, information gain, ID3 in Python, overfitting, pre- and post-pruning Learn → Quiz → Coming soon
10K-Means and Clustering Unsupervised learning, the K-means algorithm and its cost, local optima and random restarts, the elbow method and silhouette analysis, K-means++, soft K-means, hierarchical clustering and linkages, cluster evaluation metrics Learn → Quiz → Coming soon
11Neural Networks The artificial neuron and activation functions, logic gates and XOR, multilayer perceptrons and universality, gradient descent, perceptron learning, back-propagation, handwritten digit recognition Learn → Quiz → Coming soon
12Transformers and Generative Models Subword tokenization and BPE, embeddings and position, self-attention with queries, keys and values, causal masking, MLP and residual connections, logits, softmax and temperature, text generation Learn → Quiz → Coming soon
13Post-training and Alignment Pretraining vs SFT vs preference learning, reward models and RLHF, the KL constraint, reward hacking and Goodhart's law, DPO, human and AI feedback, outcome vs process supervision, verifiable rewards, evaluation Learn → Quiz → Coming soon
14Evaluation, Metrics and Data Analysis Task vs metric vs evaluator, precision, recall and F1, BLEU, ROUGE-L and COMET, LLM-as-a-judge and its biases, reading plots, subgroup analysis, distribution shift, data leakage and contamination, uncertainty, human evaluation Learn → Quiz → Coming soon

Recommended projects: take part in SemEval-2027

SemEval is the yearly international workshop on semantic evaluation: organisers publish a task with data and a metric, teams build systems, and all systems are scored on the same hidden test set.

The 11 tasks

Task 9: Analysis of Multimodal Framing in the News

We are among the organisers of Task 9: Dr. Dimitar Dimitrov, Elitsa Yotkova and Prof. Ivan Koychev, together with Giovanni Da San Martino, Preslav Nakov, Jakub Piskorski and colleagues from Padova, MBZUAI, Helsinki, Porto, Beira Interior and ETH Zurich. It builds on the SemEval-2023 task on persuasion techniques, framing and news genre.

Framing is choosing which aspects of an issue to make salient, so that a reader takes away a particular meaning. Images can reinforce, complement or contradict the framing of the text.

Led by

Labs · Teaching Assistant · Author of these notes

Elitsa Yotkova

Master's student in Information Retrieval and Knowledge Discovery @ Sofia University, ex-Google, Uber

Previously at

Labs · Teaching Assistant · Author of these notes

Kristina Kalemdzhieva

Master's student in Information Retrieval and Knowledge Discovery @ Sofia University, ex-AWS

Previously at

Lectures

Prof. Ivan Koychev

Sofia University "St. Kliment Ohridski", Faculty of Mathematics and Informatics

The course is also taught by other teaching assistants; this site contains only our lab notes.