This paper investigates the impact of different Byte Pair Encoding (BPE) configurations, specifically, merge operations on neural machine translation (NMT) performance for the Filipino-Cebuano language pair across various text domains. Results demonstrate that smaller BPE configurations, notably 2k, 5k, and 8k consistently yield higher BLEU scores, indicating improved translation quality through finer tokenization granularity. Conversely, larger BPE configurations and the absence of BPE result in lower BLEU scores, suggesting a decline in translation quality due to coarser tokenization. Additionally, these findings help us understand how the size of the model and how finely we break down words affect the quality of translations. This knowledge will be useful for improving translation systems, especially for languages that don’t have many parallel texts available for training.

Building a robust machine translation (MT) system requires a large amount of parallel corpus which is an expensive resource for low-resourced languages. The two major languages being spoken in the Philippines which are Filipino and Cebuano have an abundance in monolingual data that this study took advantage of attempting to find the best way to automatically generate parallel corpus out from monolingual corpora through the use of bitext alignment. Byte-pair encoding was applied in an attempt to optimize the alignment of the source and target texts. Results have shown that alignment was best achieved without segmenting the tokens. Itermax alignment score is best for short-length sentences and match or argmax alignment score are best for long-length sentences.