theoretical (and not thinking about practical problems)

dogmatic, opinionated

determined and stubborn when trying to solve or complete something

determined, persistent

put forward as dogmas; (of a person, statement) expressing opinions in an arrogant way

dictatorial, opinionated

an animal that is the young of a horse and a donkey; a slipper without a heel

stubborn

not easily agreeing to an argument or being persuaded; stubborn

stubborn, determined

often expressing (too much) confidence in one's own opinion

believing very strongly and conveying it

(of a person) deliberately continuing to do wrong; (of behaviour) unreasonable

mean, ornery; troublesome

decided and fixed; (of opinions, habits etc) fixed and not to be changed; unmoving; a group of games (in tennis etc); a group of similar things; the position (of the body, clothes etc)

decided

(of a person) having a strong, determined will; difficult to deal

obstinate, unyielding

not prepared to make any compromise

stubborn

not hesitating

steadfast

(of a person) determined to have one's own way; intentional

stubborn, obstinate