Mae vs. Yw?

[llituro]

I am getting very confused about when to use some form of "Mae/Maen" and when to use "Yw/Ydy" and what not. Any sort of information or chart would be welcome. Thank you.

[MrGWallCymraeg]

Mae = there is/are; he/she is
Maen = they are
Ydy? = Is/Does he/she?
Ydy = yes, he/she does/is

Ydy/Yw = both used emphatically to mean is/are.

Ydy is always used with a question; yw is never used (grammatically) with a question.

[SirFurboy]

Take a look at the present tense chart here:

https://en.wikibooks.org/wiki/Welsh/Verbs

or you may find Mark Nodine's course easier:

https://www.cs.cf.ac.uk/fun/welsh/Lesson02.html

You are not specific where the issue arises, but as you mention "mae" and "yw" it is possible you are tripping up on the emphatic constructions.

Consider:
mae e'n ddysgwyr = he is a learner

But:

dysgwyr yw e = he is a LEARNER (i.e with emphasis that he is a learner, not something else)

In Welsh the verb belongs at the front of the sentence but if you move something else to the front, you give it emphasis. The problem is that the emphatic verb can change the way it looks. Mae and yw are both the verb "to be" in the present tense, third person. However mae is not used in the emphatic form, but yw is.

I should add that "mae" and "maen" are very irregular forms of "to be". Other forms are not so tricky.