[Locked] YUROP

If you zoom in, you can read what those abbreviations mean and it's all different math expressions. So I guess it's something else that just reminds people of a periodic table. Also the word "maths" can be read on the poster, so another indication that this is not a periodic table...

If you zoom in, it's clearly a "periodic table of math". You see this sort of thing sometimes, where someone will make a chart composed of prominent objects, categories, or concepts in a field, arranged to look like the periodic table of chemical elements. Like the "periodic table of beer styles" or "periodic table of musical genres", typically with abbreviations similar to chemical symbols.

This one has elements like "Decimal Point", "Numerator", "Cosine Rule", "Rotation", etc.