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CSTinyLlama-1.2B is a Czech language model continously pretrained on 168b training tokens from English TinyLLama-2.5T model. Model was pretrained on ~67b token Large Czech Collection using Czech tokenizer, obtained using our vocabulary swap method. Training was done on Karolina cluster.

BUT LM Model Roster


Below we

  • (i) demonstrate the convergence speed of released model (TINYLLAMA1.2B_cztokenizer64k_align1.7k_tllama1.1B_C2048_lr1e-04_150k, at 160k step).
  • (ii) justify the contributions of our vocabulary swap method by comparing the swapped model with model trained from scratch (using same hyperparameters) scratch_cztokenizer64k_tllama1.1B_C2048_lr1e-04_150k. We swap 1.7K tokens in this run, similarly as for our other models (see Czech-GPT-2-XL-133k)

Train Cross-Entropy

Test Perplexity

Training parameters

Not mentioned parameters are the same as for TinyLLama-2.5T.

Name Value Note
dataset_type Concat Sequences at the model's input were concatenated up to $max_seq_len, divided by EOS token.
tokenizer_size 64k
max_seq_len 2048
batch_size 512
learning_rate 1.0e-4
optimizer LionW
optimizer_betas 0.9/0.95
optimizer_weight_decay 0
gradient_clipping_max_norm 1.0
attn_impl flash2
fsdp SHARD_GRAD_OP (optimized for A100 40GB GPUs)
precision bf16
scheduler cosine
scheduler_warmup 100 steps
scheduler_steps 200,000
scheduler_alpha 0.1 So LR on last step is 0.1*(vanilla LR)


import torch
import transformers
from transformers import pipeline

name = 'BUT-FIT/CSTinyLlama-1.2B'

config = transformers.AutoConfig.from_pretrained(name, trust_remote_code=True)
model = transformers.AutoModelForCausalLM.from_pretrained(

tokenizer = transformers.AutoTokenizer.from_pretrained(name, trust_remote_code=True)

pipe = pipeline('text-generation', model=model, tokenizer=tokenizer, device='cuda:0')

with torch.autocast('cuda', dtype=torch.bfloat16):
        pipe('Nejznámějším českým spisovatelem ',

Training Data

We release most (95.79%) of our training data corpus as BUT-Large Czech Collection.

Getting in Touch

For further questions, email to martin.fajcik@vut.cz.


This is a probabilistic model, it can output stochastic information. Authors are not responsible for the model outputs. Use at your own risk.


This work was supported by NAKI III program of Ministry of Culture Czech Republic, project semANT --- "Sémantický průzkumník textového kulturního dědictví" grant no. DH23P03OVV060 and by the Ministry of Education, Youth and Sports of the Czech Republic through the e-INFRA CZ (ID:90254).


  author    = {Martin Fajčík, Martin Dočekal, Jan Doležal, Karel Beneš, Michal Hradiš},
  title     = {BenCzechMark: Machine Language Understanding Benchmark for Czech Language},
  journal   = {arXiv preprint arXiv:insert-arxiv-number-here},
  year      = {2024},
  month     = {March},
  eprint    = {insert-arxiv-number-here},
  archivePrefix = {arXiv},
  primaryClass  = {cs.CL},
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Datasets used to train BUT-FIT/CSTinyLlama-1.2B