Lectures

1. Introduction

 3 October Slides Questions

• What are dialogue systems
• Common usage areas
• Task-oriented vs. non-task oriented systems
• Closed domain, multi-domain, open domain
• System vs. user initiative in dialogue
• Standard dialogue systems components
• Research forefront
• TTS audio examples: formant, concatenative, HMMs, neural

2. Data & Evaluation

 10 October Slides Dataset Exploration Questions

• Types of dialogue datasets
• Dataset splits
• Intrinsic vs. extrinsic evaluation
• Objective vs. subjective evaluation
• Evaluation metrics for dialogue components

3. Neural Nets Basics

 17 October Slides Questions

• machine learning as function approximation
• machine learning problems (classification, regression, structured prediction)
• input features (embeddings)
• network shapes -- feed forward, CNNs, RNNs, attention, Transformer

4. Training Neural Nets

 24 October Slides MultiWOZ 2.2 Loader Questions

• supervised training: gradient descent, backpropagation, cost
• learning rate, schedules & optimizers
• self-supervised: autoencoding, language modelling
• pretraining, finetuning, prompting
• unsupervised: GANs, clustering
• reinforcement learning (short intro), RLHF

5. Natural Language Understanding

 31 October Slides Questions

• problems of NLU
• common meaning representations -- intents + slots
• delexicalization, simple approaches
• various neural approaches to NLU (network shapes & training tasks)
• joint intent & slot models
• pretrained models, less supervision

6. Dialogue Management (1)

 7 November Slides Prompting Llama for responses on MultiWOZ Questions

• dialogue state tracking & action selection/policy
• dialogue state, belief state
• static & dynamic trackers, various approaches
• introduction to policies
• reinforcement learning, user simulator

Homework Assignments

There will be 6 homework assignments + 2 bonuses, each for a maximum of 10 points. Please see details on grading and deadlines on a separate tab.

Assignments should be submitted via Git – see instructions on a separate tab.

All deadlines are 23:59:59 CET/CEST.

Note: If you don't have a faculty Gitlab account yet, please create one as soon as possible (see the instructions). Don't wait until the deadline! It takes 5 minutes, and if you don't do it, you won't have any way of submitting.

Index

1. Dataset Exploration

2. MultiWOZ 2.2 Loader

3. Prompting Llama for responses on MultiWOZ

1. Dataset Exploration

 Presented: 10 October, Deadline: 29 October

Task

Your task is to select one dialogue dataset, download and explore it.

1. Find out (and mention in your report):

• The name of the dataset

• What kind of data it is (domain, modality)
• Where you downloaded it from (include the original URL)
• How it was collected
• What kind of dialogue system or dialogue system component it's designed for
• What kind of annotation is present (if any at all), how was it obtained (human/automatic)
• What format is it stored in
• What is the license

Here you can use the dataset description/paper that came out with the data. The papers are linked from the dataset webpages or from here. If you can't find a paper, ask us and we'll try to help. If you can't find some of the information in the paper, mention it in your report.

2. Measure (and enter into your report):

• Total data length (in terms of dialogues, turns, sentences, words; separately for user/system)
• Mean/std dev dialogue lengths (in terms of dialogues, turns, sentences, words; separately for user/system)
• Vocabulary size (separate for user/system)
• Shannon entropy over words in User/system turns (see slide 21 in Lecture 2)

Here you should use your own programming skills. If your dataset has a train/dev/test split, use the training set. If there's no clear separation between a user and a system (e.g. human-human chitchat data, or NLU-only data), provide just the overall numbers.

3. Have a closer look at the data and try to make an impression -- does the data look natural? How difficult do you think this dataset will be to learn from? How usable will it be in an actual system? Do you think there's some kind of problem or limitation with the data? Write a short paragraph about this in your report.

Things to submit:

• A short summary detailing all of your findings (basic info, measurement, impressions) in Markdown as hw1/README.md.
• Your code for analyzing the data as hw1/analysis.py or hw1/analysis.ipynb.

See the submission instructions here (clone your Gitlab repo and add a new merge request).

Datasets to select from

Primarily one of these:

• DailyDialog (http://yanran.li/dailydialog.html)
• Schema-Guided Dialogue (https://github.com/google-research-datasets/dstc8-schema-guided-dialogue)
• CrossWOZ (https://github.com/thu-coai/CrossWOZ)
• Clinc-OOS (https://github.com/clinc/oos-eval)
• ConvBank (https://gitlab.com/ucdavisnlp/dialog-parsing)
• Multi3WOZ (https://github.com/cambridgeltl/multi3woz)
• MetaLWOz/DSTC8 (https://www.microsoft.com/en-us/research/project/metalwoz/)
• PersonaChat (https://github.com/facebookresearch/ParlAI/tree/main/parlai/tasks/personachat, direct download link here, use the train_none_original data)
• Wizard of Wikipedia (https://parl.ai/projects/wizard_of_wikipedia/)

Others:

• AirDialogue (https://github.com/google/airdialogue)
• Edina Self-dialogue (https://github.com/jfainberg/self_dialogue_corpus)
• Empathetic Dialogues (https://github.com/facebookresearch/EmpatheticDialogues)
• FB Semantic Parsing for Dialogue (https://www.aclweb.org/anthology/D18-1300/, http://fb.me/semanticparsingdialog)
• FB multilingual (https://arxiv.org/pdf/1810.13327.pdf, https://fb.me/multilingual_task_oriented_data)
• GraphWOZ (https://arxiv.org/abs/2211.12852, https://github.com/ntwalker/GraphWOZ)
• Holl-E (https://github.com/nikitacs16/Holl-E)
• HR-MultiWOZ (https://github.com/amazon-science/hr-multiwoz-tod-llm-agent)
• HWU NLU Evaluation data (https://github.com/xliuhw/NLU-Evaluation-Data)
• KG-Copy Data (https://github.com/SmartDataAnalytics/KG-Copy_Network, the data subdirectory)
• MS Dialogue Challenge Data (https://github.com/xiul-msr/e2e_dialog_challenge)
• Mimic & Rephrase (https://www.aclweb.org/anthology/K19-1037, https://github.com/square/MimicAndRephrase/)
• PolyAI Task-specific – Banking (https://github.com/PolyAI-LDN/task-specific-datasets)
• PolyAI Task-specific – Span Extraction (https://github.com/PolyAI-LDN/task-specific-datasets)
• SPOLIN improv data (https://github.com/wise-east/spolin)
• Snips (https://github.com/snipsco/nlu-benchmark/tree/master/2017-06-custom-intent-engines)
• Taskmaster-1 (https://ai.google/tools/datasets/taskmaster-1)
• Taskmaster-2 (https://research.google/tools/datasets/taskmaster-2/)
• Topical Chat (https://github.com/alexa/Topical-Chat)
• Ubuntu Dialogue (https://github.com/rkadlec/ubuntu-ranking-dataset-creator)

Further links

Dataset surveys (broader, but shallower than what we're aiming at):

• https://breakend.github.io/DialogDatasets/
• https://github.com/AtmaHou/Task-Oriented-Dialogue-Dataset-Survey

2. MultiWOZ 2.2 Loader

 Presented: 24 October, Deadline: 26 November

NOTE: The code & assignment have been updated significantly. The deadline was extended by 2 weeks. Before you start any implementation, make sure you update from upstream!

Task

Your task is to create a component that will load the task-oriented MultiWOZ 2.2 dataset and process the data so it is prepared for model training. The component will consist of two Python classes -- one to hold the data, and one to prepare the training batches.

In later assignments, you will build an LLM based model (a prompted one similar to this one and a finetuned one similar to SOLOIST) using the data provided by this loader. Note that this means that the next assignments depend on this one.

We prepared some code templates for you to guide your implementation. You should not need to modify the code already present in the templates. If you need to, you can do so, but please comment on your code changes in the MR. The bits that are waiting for your implementation are highlighted with # TODO: in diallama/mw_loader.py, diallama/generate.py and hw2/test.py.

Note that to use the provided code, you'll need to install the dependencies provided in the requirements.txt. They can be installed easily via pip install -r requirements.txt.

Data background

MultiWOZ 2.2 is a task-oriented conversational dataset labeled with dialogue acts. It contains around 10k conversations between the user and a Cambridge town info centre (system). The dialogues are about certain topics: restaurants, hotels, trains, taxi, tourist attractions, hospital, and police. You can find more details in the dataset repository.

You can write your own dataset loader from the original format (see the dataset) but we recommend using the Huggingface Datasets library version.

This is how the data looks like if you load it using Huggingface Datasets: Each entry in the dataset represents one dialog. The information we are interested in is contained in the field turns, which is a dictionary with the following important keys:

• speaker: Role associated with the speaker. It's either 0 (user) or 1 (system).
• utterance: String representation of the dialogue utterances.
• dialogue_acts: Structured parse of the system utterances into dialog acts (only in system utterances). It contains slot names and corresponding span_info (location of the slot in the utterance, which will come in handy later).
• frames: Present only in user utterances. Structured representation of the user's belief state.

Each of these keys is mapped to a list with labels for the corresponding turns, i.e. turns['speaker'][0] contains information for the speaker of the first turn and turns['speaker'][-1] of the last one. The dataset contains the train, validation and test splits. Please respect them!

Note that MultiWOZ also contains a database (and you need database queries for your system to work correctly), but we'll address that later.

Dataset class

You need to implement the following properties for the Dataset class inside diallama/mw_loader.py:

• It loads the data and process it into individual training examples (containing contexts & system responses so far; we'll skip dialogue states and the database for now).
  • Note that we are modelling only system responses, so each training example should correspond to one system response. User utterances should not be treated as response, they're only part of the context.
• Each loaded example is a dictionary of the folowing structure:

  {
      'context': list[str],  # list of utterances preceeding the current system utterance/response
      'utterance': str,  # the string with the current system utterance/response
      'delex_utterance': str,  # the string with the current response which is delexicalized, i.e. slot values are 
                               # replaced by corresponding slot names in the text.
  }
  

• Each dialogue of n turns will yield n // 2 examples, each with progressively longer context (starting from a context of length 1, up to n-1 turns of context).
• It distinguishes between data splits, i.e. it can be parameterized by split type (train, validation, test).
• It can truncate long contexts to k last utterances, where k is a parameter of the class.
• It contains delexicalized versions of the utterances (where slot values are replaced with placeholders). You can use the data field dialogue_acts and its fields span_end, span_start for localizing the parts suitable for delexicalization. Replace those parts with the corresponding slot names from act_slot_name enclosed into brackets, e.g., [name] or [pricerange].
  • For example, you should have I found [count] [pricerange] restaurants in the [area] based on the utterance I found 10 cheap restaurants in the north.

Batch encoding (inside the GenerationWrapper class)

Machine learning models usually work with numbers and matrices. That is why we also need to convert strings in our batches to integer IDs. Since this will be the same for both prompting and finetuning, we moved the corresponding code to the class that will deal with generation in either case, i.e. GenerationWrapper in diallama/generate.py

This means that you'll also need to implement a collate function (collate_fn) inside GenerationWrapper that has the following properties:

• It is able to work with batches coming from torch.utils.data.DataLoader (lists of examples).

• It uses a tokenizer passed in the constructor to split inputs into subword tokens and assign them IDs. Note the tokenizer must be compatible with the model you'll be using.

• It converts the whole batch to a single dictionary (output) of the following structure:

  output = {
      'utterance': list[list[int]],  # tokenized utterances (list of subword ids from the current dialogue turn) 
                                     # for all batch examples
      'delex_utterance': list[list[int]],  # tokenized and delexicalized utterances (list of subword ids 
                                           # from the current dialogue turn) for all batch examples
  }
  

  where {k : output[k][i] for k in output} should correspond to i-th example of the original input batch.

Test script

The test script is in hw2/test.py in your repo. Here, we simply test out the code -- load the dataset and print out a few things. Your task here is to load the model and tokenizer. We want to use the meta-llama/Llama-3.2-1B-Instruct model, which is just about the right combination of capable enough and small enough to fit onto small GPUs. Load the model and its tokenizer using Huggingface's auto methods, i.e., AutoModelForCausalLM.from_pretrained and AutoTokenizer.from_pretrained.

Note that meta-llama/Llama-3.2-1B-Instruct is a gated model. This means you need to set up a Huggingface account and agree to Llama3.2's terms and conditions on the model page. You can then get an access token under your Huggingface settings. Just click on Create a new token, then tick Read access to contents of all public gated repos you can access, give it some name (anything) and click Create token. Make sure you save the token. Whenever you create a model or tokenizer, make sure you pass token=<your access token> in your code.

If you don't feel comfortable agreeing to Llama terms and conditions, feel free to use Qwen/Qwen2.5-0.5B-Instruct instead, or ask Ondrej and he'll lend you his access token.

Things to submit:

• Your dataset class implementations inside diallama/mw_loader.py.
• Your collation function implementations inside diallama/generate.py.
• Your model & tokenizer loading inside hw2/test.py.
• Output of hw2/test.py run on your data (test set is used by default), as hw2/output.txt. Have a look at what the script is doing, that'll help you with your implementation.

3. Prompting Llama for responses on MultiWOZ

 Presented: 7 November, Deadline: 12 December

Before you start any implementation, make sure you update from upstream! The code is completely reworked for this assignment.

In this assignment, you'll need to prompt your model (i.e. Llama-3.2-1B-Instruct in most cases) and ask it to provide replies for various queries relating to hotels. We'll ignore state tracking and database for now, that will come later on. For now, it suffices that the model will give you some reasonable answer, it doesn't necessarily have to be true :-).

To do that, you'll need to implement a bunch of things:

• Finish the collate function and format the prompt properly
• Write the decoding part, using Huggingface's generate() function
• Prepare multiple prompts and multiple generation settings and test them out.

Most of your implementation will be in the GenerationWrapper class, which deals with all things related to decoding. Finetuning the model will come later.

Prompt templating -- finishing the collate function

First of all, you need to finish the GenerationWrapper.collate_fn method you started in HW2, to correctly format the whole input prompt for the model. LLMs, especially the instruction tuned ones, use a very specific prompt formatting. You should use your tokenizer's apply_chat_template function for this. It'll handle all the formatting for you. Note that GenerationWrapper has the tokenizer passed in upon creation (see its __init__ method).

The LLM input prompt (for an instruction-tuned LLM which you chat with, like you would with ChatGPT) has multiple parts:

• Your chat with the LLM always uses a system prompt at the beginning, telling the LLM what its general role is (“You are an assitant...”).
• In our case, the whole chat will basically just consist of a single turn, where you supply the response prompt, i.e., instruction to the LLM to provide a response at the given point in the dialogue. This prompt should include the whole dialogue context/history, formatted in some appropriate form (e.g. each turn on a new line, prepended with alternating User: and Assistant:; you know the last one is supposed to be a user turn).

So the whole input prompt will include the system prompt + response prompt relating to the current sentence the system wants to deal with, in the chat template format. Let your collate_fn method return the whole tokenized font. It's a good idea to print it out so you see how it looks like (you might need to do it for debugging anyway).

Since the system prompt and the response prompt are parameters passed to the GenerationWrapper class upon creation, you don't need to care about their exact values here (but you will do that in a second).

Note: You may also want to store the attention mask for the prompt, and pass it to the decoding (see below). It's not strictly necessary now (you'll get some annoying warnings but it'll work), but we'll use this in HW4. For now, you also don't need to store the attention mask, it'll just be a vector of 1's with the same shape as the vector for the prompt.

Decoding

The second thing you need to implement is the output generation inside the GenerationWrapper.generate_response method. Here, you need to:

• Get your input context formatted as a prompt using the GenerationWrapper.collate_fn method you just finished.
• Feed the prompt into your LLM using self.model.generate() and use the GenerationConfig parameter passed into GenerationWrapper.generate_response.
• When you get the model's output, it'll contain your input prompt as well as the model's output following it. You need to cut off the prompt and return just the next response in the dialogue.

Test script

Now it's time to try out what you coded, using hw3/test.py, where we try out multiple prompts & multiple generation settings. This script needs the actual prompts and generation settings values, so you'll need to fill it in.

• Fill in a system prompt, telling the LLM what role it should play (SYSTEM_PROMPT).
• Fill in at least 3 significantly different variants of the response prompt (RESPONSE_PROMPTS). You can try out lexicalized vs. delexicalized responses, or different level of detail for the instructions (specifying the response format, what the model can and cannot do, etc.).
• Fill in 3 different GenerationConfig options into GENERATION_CONFIGS. You can have a look at this tutorial, to find out what settings there are and how they differ. In any case, make sure to use max_new_tokens and set it below 100, so your code doesn't take forever (you don't need longer replies anyway). Note that the way the code is set up, only the first prompt will be used with all settings, the following prompts will only use the first setting.
• Fill in the code for loading your model & tokenizer, just like you did in HW2.

Finally, store the outputs of your script as hw3/output.txt. Look how the individual settings differ, and write up a short paragraph in Markdown or plain text in hw3/report.md (5-10 sentences). We'll look at more rigorous evaluation on the actual dataset later, but this is how you would play with prompting with LLMs anyway.

Note: Running this on your computer's CPU will most likely be annoyingly slow, so you'll want to use a GPU. You can use Google Colab, which provides GPUs for free for a limited time spans, typically enough to run this. You can also get an account on our in-house AIC student computing cluster (Ondrej will get your accounts created and distribute passwords soon). Before you work on AIC, make sure you read the instructions! You can prepare and debug your code even without a GPU, then only run the actual generation once you have access to a GPU.

Things to submit

• Your finished collation code (prompt formatting) and generation/decoding code in diallama/generate.py.
• Your prompt and generation settings as well as model loading in hw3/test.py.
• The output of your script in hw3/output.txt.
• Your short commentary on how the models works (or doesn't work) under the different settings, in hw3/report.md.

• Submission instructions
• Cluster tips

Homework Submission Instructions

All homework assignments will be submitted using a Git repository on MFF GitLab.

We provide an easy recipe to set up your repository below:

Creating the repository

1. Log into your MFF gitlab account. Your username and password should be the same as in the CAS, see this.
2. You'll have a project repository created for you under the teaching/NPFL099/2024 group. The project name will be the same as your CAS username. If you don't see any repository, it might be the first time you've ever logged on to Gitlab. In that case, Ondřej first needs to run a script that creates the repository for you (please let him know on Slack/email). In any case, you can explore everything in the base repository. Your own repo will be derived from this one.
3. Clone your repository.
4. Change into the cloned directory and run

git remote show origin

You should see these two lines:

* remote origin
  Fetch URL: git@gitlab.mff.cuni.cz:teaching/NPFL099/2024/your_username.git
  Push  URL: git@gitlab.mff.cuni.cz:teaching/NPFL099/2024/your_username.git

5. Add the base repository (with our code, for everyone) as your upstream:

git remote add upstream https://gitlab.mff.cuni.cz/teaching/NPFL099/base.git

6. You're all set!

Submitting the homework assignment

1. Make sure you're on your master branch

git checkout master

2. Checkout new branch:

git checkout -b hwX

3. Solve the assignment :)

4. Add new files (if applicable) and commit your changes:

git add hwX/solution.py
git commit -am "commit message"

5. Push to your origin remote repository:

git push origin hwX

6. Create a Merge request in the web interface. Make sure you create the merge request into the master branch in your own forked repository (not into the upstream).

    Merge requests -> New merge request
   

7. Wait a bit till we check your solution, then enjoy your points :)!
8. Once approved, merge your changes into your master branch – you might need them for further homeworks (but feel free to branch out from the previous homework in your next one if we're too slow with checking).

Updating from the base repository

You'll probably need to update from the upstream base repository every once in a while (most probably before you start implementing each assignment). We'll let you know when we make changes to the base repo.

To upgrade from upstream, do the following:

1. Make sure you're on your master branch

git checkout master

2. Fetch the changes

git fetch upstream master

3. Apply the diff

git merge upstream/master master

Automated Tests

You can run some basic sanity checks for homework assignments -- they are included in your repository (make sure to upgrade from upstream first). Note that the tests require stuff from requirements.txt to be installed in your Python environment. The tests assume checking in the current directory, they assume you have the correct branches set up.

For instance, to check hw1, run:

./run_tests.py hw1

By default, this will just check your local files. If you want to check whether you have your branches set up correctly, use the --check-git parameter. Note that this will run git checkout hw1 and git pull, so be sure to save any local changes beforehand!

Always update from upstream before running tests, we're adding checks for new assignments as we go. Some may only be available at the last minute, we're sorry for that!

AIC Cluster Computation Tips

This is just a short primer for the AIC wiki – better read that one, too. But definitely read at least this text before you start working with AIC.

Login

Use the command

ssh LOGIN@aic.ufal.mff.cuni.cz

where LOGIN is your SIS username.

On the head node

When you log on to AIC, you're at the cluster head node. Do not compute here – this just for launching computation jobs, copying files and such. All of your computation jobs will run on one of the CPU/GPU nodes. (You can run the terminal multiplexing program on the head node.)

Workflow

There are two ways to compute on the cluster:

1. submitting a batch script containing the commands you wish to run,
2. executing commands in an interactive shell.

You should use a batch script for running longer computations. The interactive shell is useful for debugging.

Batch scripts

Use the sbatch command to submit your jobs (i.e. shell scripts) into a queue. For running a python command, simply create a shell script that has one line – your command with all the parameters you need.

You can either specify the parameters in the script or on the command line.

Here are two equivalent ways of specifying a GPU job with 2 CPU cores, 1 GPU and 16G system RAM (all GPUs have 11G memory):

Using SBATCH directives

1. Create a file job_script.sh:

#!/bin/bash
#SBATCH -J hello_world					  # name of job
#SBATCH -p gpu      					  # name of partition or queue (if not specified default partition is used)
#SBATCH --cpus-per-task=2                 # number of cores/threads per task (default 1)
#SBATCH --gpus=1                          # number of GPUs to request (default 0)
#SBATCH --mem=16G                         # request 16 gigabytes memory (per node, default depends on node)

# here start the actual commands
sleep 5
echo "Hello I am running on cluster!"

2. Execute the command:

sbatch job_script.sh

Using command-line parameters

1. Create a file job_script.sh:

#!/bin/bash

sleep 5
echo "Hello I am running on cluster!"

2. Execute the command:

sbatch -J hello_world -p gpu -c2 -G1 --mem 16G job_script.sh

Have a look at the AIC wiki or man sbatch for all the command-line parameters.

(Note: long / short flags can be used interchangeably for both approaches.)

Interactive jobs

You can get an interactive console using srun.

The following command will run bash with the same resources as in the previous example:

srun -J hello_world -p gpu -c2 -G1 --mem=16G --pty bash

Important notes

• Always request the resources you'll need! (both for the batch and interactive jobs).
• With interactive jobs, don't forget to exit the console after use – you're blocking the GPU and whatever you reserve as long as the console is open!
• Don't submit too many jobs at a time (don't overfill the cluster, leave space for others).
• You can't request more than 8 CPU cores or 1 GPUs.

Other commands

• Use sinfo to list the available queues.
• Use squeue --me or squeue -u LOGIN (where LOGIN is your username) to check your jobs.
• Use squeue to see every job currently running on the cluster.
• Use scancel JOB_ID to cancel a job.

Tips for efficient development

• terminal multiplexing: byobu (or tmux, screen) allows you to have multiple terminal sessions and keeping everything open even if you lose connection (see a quick primer on byobu).
• SSH connection: mosh is able to reestablish the SSH connection after the connection is interrupted (unstable internet, turning the computer off, etc.).
• file management: you can access the AIC filesystem using SFTP: sftp://LOGIN@aic.ufal.mff.cuni.cz
  • many default Linux file managers (Nautilus, Nemo, etc.) support SFTP natively (simply press Ctrl+L),
  • for Windows use WinSCP,
  • for command line access use mc (F9-“Shell link”) or rsync.
• development: the SSH plugin for VS Code enables you to code in IDE directly on the cluster.
• Python:
  • virtual environments – managing Python packages locally,
  • pdb++, pudb, ipdb – advanced Python command line debugging,
  • gpustat – overview of GPUs on the current node,
  • miniconda – if you need to use different version than Python 3.10.6 (which is the system one).

Links

• SLURM tutorial for ÚFAL cluster: https://wiki.ufal.ms.mff.cuni.cz/slurm
• SLURM cheatsheet: https://www.carc.usc.edu/user-information/user-guides/hpc-basics/slurm-cheatsheet
• sbatch manpage: https://manpages.org/sbatch

Exam Question Pool

The exam will have 10 questions from the pool below. Each question counts for 10 points. We reserve the right to make slight alterations or use variants of the same questions. Note that all of them are covered by the lectures, and they cover most of the lecture content. In general, none of them requires you to memorize formulas, but you should know the main ideas and principles. See the Grading tab for details on grading.

Introduction

• What's the difference between task-oriented and non-task-oriented systems?
• Describe the difference between closed-domain, multi-domain, and open-doman systems.
• Describe the difference between user-initiative, mixed-initiative, and system-initiative systems.
• List the main components of a modular task-oriented dialogue system (text/voice-based)
• What is the task (input/output) of speech recognition in a dialogue system?
• What is the task (input/output) of speech synthesis in a dialogue system?

Data & Evaluation

• What are the usual approaches to collecting dialogue data (name at least 2)?
• How does Wizard-of-Oz data collection work?
• What’s the difference between intrinsic and extrinsic evaluation?
• What is the difference between subjective and objective evaluation?
• What are the common options of getting people to evaluate your system?
• What are some evaluation metrics for non-task-oriented systems (chatbots)?
• How would you evaluate NLU (both slots & intents)?
• Explain an NLG evaluation metric of your choice.
• Describe how BLEU works (in principle, exact formulas not needed).
• Show at least 2 examples of subjective (human) evaluation metrics for dialogue systems.
• What is significance testing and what is it good for?
• Assume you have dialogue systems A and B, and A performs better than B in terms of response BLEU on a dataset of 100 dialogues. Describe how you’d test for significance.
• Why do you need to evaluate on a separate test set?

Neural Nets Basics

• What's the difference between classification and regression as a machine learning problem?
• Describe the task of sequence prediction (=autoregressive generation).
• What's the difference between classification and ranking as a machine learning problem?
• What's the difference between sequence labeling and sequence prediction?
• What is an embedding, what units can it relate to, and how can you obtain it?
• What are subwords and why are they useful?
• What's an encoder-decoder model and how does it work?
• How does an attention model work?
• What's the main principle of operation for convolutional networks?
• What's the difference between LSTM/GRU-based and Transformer-based architecture?
• Describe the basics of a Transformer language model.
• What's a pretrained language model?

Training Neural Nets

• Describe the principle of stochastic gradient descent.
• Why is it important to choose an appropriate learning rate?
• Describe an approach for learning rate adjustment of your choice.
• What is dropout, what is it good for and why does it work?
• What’s a variational autoencoder and how does it differ from a “regular” autoencoder?
• What is masked language modeling?
• How do Generative Adversarial Networks work?
• Describe the principle of the pretraining+finetuning approach.
• How does clustering work?
• What is self-supervised training and why is it useful?
• Describe 2 examples of a self-supervised training task.
• Can you apply a pretrained language model for a new task without finetuning it at all?
• How can you finetune a language model without updating all the parameters?
• What's instruction tuning and what is it good for?

Natural Language Understanding

• Design a (sketch) of an NLU neural architecture that joins intent detection and slot tagging.
• Describe language understanding as classification and language understanding as sequence tagging.
• What is delexicalization and why is it helpful in NLU?
• Describe one of the approaches to slot tagging as sequence tagging.
• What is the IOB/BIO format for slot tagging?
• How can you use pretrained language models (e.g. BERT) for NLU?
• How can you combine rules and neural networks in NLU?
• How can an NLU system deal with noisy ASR output? Propose an example solution.

Dialogue State Tracking

• What is the point of dialogue state tracking in a dialogue system?
• What is the difference between dialogue state and belief state?
• What's the difference between a static and a dynamic state tracker?
• What's a partially observable Markov decision process?
• Describe a viable architecture for a belief tracker.
• What is the difference between state trackers as classifiers vs. as candidate rankers?
• Describe the principle of state tracking as span selection.

Dialogue Policies

• Describe the basic reinforcement learning setup (agent, environment, actions, rewards).
• Map the general reinforcement learning setup to a dialogue system situation.
• Why is reinforcement learning preferred over supervised learning for training dialogue managers?
• What are V and Q functions in a reinforcement learning scenario?
• What's the difference between actor and critic methods in reinforcement learning?
• Describe a Deep Q Network.
• Describe the REINFORCE approach.
• What’s the main principled difference between Deep Q-Networks and Policy Gradient methods?
• What are actor-critic reinforcement learning methods?
• What’s the difference between on-policy and off-policy optimization?
• Why do you typically need a user simulator to train a reinforcement learning dialogue policy?
• Give an example of possible turn-level or dialogue-level rewards for RL optimization.
• What is a user simulator? What are some common approaches to building one?

Natural Language Generation

• What are the main steps of a traditional NLG pipeline – describe at least 2.
• Describe a chosen handcrafted approach to NLG.
• What are the main problems with vanilla neural NLG systems (base RNN/Transformer)?
• What is a copy mechanism/pointer network?
• What is delexicalization and why is it helpful in NLG?
• Describe a possible neural approach to NLG with an approach to combat hallucination.
• How can you reduce NLG hallucination by altering the training data?
• How can you use pretrained language models in NLG?
• How can you combine templates with neural approaches for NLG?
• What are the typical decoding approaches in NLG? Explain & contrast at least 2.

End-to-end Models

• What are some pros and cons of end-to-end models over traditional modular ones?
• Describe an example structure of an end-to-end dialogue system.
• Describe the Sequicity (2-step decoding) model.
• Describe an end-to-end model based on pretrained language models.
• How would you adapt a pretrained language model for an end-to-end dialogue system?
• What are “soft” database lookups in end-to-end dialogue systems?
• How would you use reinforcement learning to train an end-to-end model?
• Why is it a bad idea to train end-to-end dialogue systems only with reinforcement learning on word level?
• How can you increase consistency (w.r.t. dialogue state) in an end-to-end model?

Chatbots

• What are the three main approaches to building chatbots?
• How does the Turing test work? Does it have any weaknesses?
• What are some techniques rule-based chatbots use to convince their users that they're human-like?
• Describe how a retrieval-based chatbot works.
• Why is plain seq2seq-based architecture for chatbots problematic?
• Describe an example approach to improving diversity or coherence in a seq2seq-based chatbot.
• How can you use a pretrained language model in a chatbot?
• Describe a possible architecture of a hybrid/ensemble chatbot.
• How does retrieval-augmented generation work?

Multimodality

• How does the structure of (traditional) multimodal dialogue systems differ from non-multimodal ones?
• Give an example of 3 alternative input modalities (i.e. not voice/text).
• Give an example of 3 alternative output modalities (i.e. not voice/text).
• How would you build a multimodal end-to-end neural dialogue system (e.g. for visual dialogue)?
• Explain some problems that may occur when a dialogue system talks to two people at once.
• What’s the difference between image classification and object detection?
• How would you build a neural end-to-end image-based dialogue system (consider using pretrained components)?
• What is the task of visual dialogue about?

Linguistics & Ethics

• What are turn taking cues/hints in a dialogue? Name a few examples.
• What is a barge-in?
• What is grounding in dialogue?
• Give some examples of grounding signals in dialogue.
• What is entrainment/alignment/adaptation in dialogue?
• Describe the overgeneralization/overconfidence problem in data-driven NLP models.
• Describe the demographic bias problem in data-driven NLP models.
• Give an example of a user safety concern in dialogue systems.
• What's the problem with training neural models on private data?

Course Grading

To pass this course, you will need to:

1. Take an exam (a written test covering important lecture content).
2. Do lab homeworks (implementing an end-to-end dialogue system + other tasks).

Exam test

• There will be a written exam test at the end of tihe semester.
• There will be 10 questions, we expect at least 2-3 sentences as an answer, with a maximum of 10 points per question.
  • You may get bonus points for correct and more detailed answers.
  • A list of possible exam questions is available on the website.
• To pass the course, you need to get at least 50% of the total points from the test.
• If needed, there will be exam dates in the summer.

Homework assignments

• There will be 6 homework assignments, introduced every other week, plus some bonus assignments.
• You will submit the homework assignments into your private Gitlab repository.
• For each assignment, you will get a maximum of 10 points.
  • You may get a bonus point for nice code.
• All assignments will have a fixed deadline (typically 2-3 weeks).
  • You can ask for a deadline extension if you have a good reason, such as illness.
• If you submit the assignment after the deadline, you will get:
  • up to 50% of the maximum points if it is less than 2 weeks after the deadline;
  • 0 points if it is more than 2 weeks after the deadline.
  • Any bonus points you get will not be lowered.
• Note that most assignments depend on each other! That means that if you miss a deadline, you still might need to do an assignment without points in order to score on later assignments.
• Once we check the submitted assignments, you will see the points you got and the comments from us on Gitlab, in a comment on your merge request.
  • Please bear with us for the checking, it's harder than it looks.
  • If your unsure about your total points, feel free to ask.
• You can take the exam even if you don't reach 40 homework assignment points, but you need to get at least 40 points to get the final grade.

Grading

The final grade for the course will be a combination of your exam score and your homework assignment score, weighted 3:1 (i.e. the exam accounts for 75% of the grade, the assignments for 25%).

Grading:

• Grade 1: >=87% of the weighted combination
• Grade 2: >=74% of the weighted combination
• Grade 3: >=60% of the weighted combination
• An overall score of less than 60% means you did not pass.

In any case, you need >50% of points from the test and 40+ points (i.e. 66%) from the homeworks to pass. If you get less than the minimum from either, even if you get more than 60% overall, you will not pass.

No cheating

• Cheating is strictly prohibited and any student found cheating will be punished. The punishment can involve failing the whole course, or, in grave cases, being expelled from the faculty.
• Discussing homework assignments with your classmates is OK. Sharing code is not OK (unless explicitly allowed); by default, you must complete the assignments yourself.
• All students involved in cheating will be punished. E.g. if you share your assignment with a friend, both you and your friend will be punished.

Recommended Reading

You should be able to pass the course just by following the lectures, but here are some hints on further reading. There's nothing ideal on the topic as this is a very active research area, but some of these should give you a broader overview.

Recommended, though slightly outdated:

• Gao et al.: Neural Approaches to Conversational AI. arXiv:1809.08267

Recommended, but might be a bit too brief:

• Jurafsky & Martin: Speech & Language processing. 3rd ed. draft (chapter 15).
  • this one is really brief, but a good starting point
• McTear: Conversational AI: Dialogue Systems, Conversational Agents, and Chatbots. Morgan & Claypool 2021.
  • this one is most up-to-date, it is available as an e-book from our library):

Further reading:

• McTear et al.: The Conversational Interface: Talking to Smart Devices. Springer 2016.
  • good, detailed, but slightly outdated
• Jokinen & McTear: Spoken dialogue systems. Morgan & Claypool 2010.
  • good but outdated, some systems very specific to particular research projects
• Rieser & Lemon: Reinforcement learning for adaptive dialogue systems. Springer 2011.
  • advanced, slightly outdated, project-specific
• Lemon & Pietquin: Data-Driven Methods for Adaptive Spoken Dialogue Systems. Springer 2012.
  • ditto
• Skantze: Error Handling in Spoken Dialogue Systems. PhD Thesis 2007, Chap. 2.
  • good introduction into dialogue systems in general, albeit dated
• current papers from the field (see links on lecture slides)