Is Ibn Taymiyyah an absolute Mujtahid, and could you please elaborate on the categories of فقهاء (jurists)?

The mujtahid (independent jurist) scholars are of four types: a Muttlaq Mujtahid (Absolute Mujtahid), who is one who meets the conditions of ijtihad and independently derives Islamic rulings from their proofs without being bound by the madhhab (school of thought) of anyone. Some later scholars have included Shaykh al-Islam Ibn Taymiyyah in this category. The other types are: a mujtahid within the madhhab of his imam or another, a mujtahid in a specific branch of knowledge, and a mujtahid in a single issue or multiple issues. Al-Mardawi indicated that the Absolute Mujtahid has been absent for a long time due to the lack of strong resolve and lukewarm aspirations, even though the matter is easier now due to the codification of Hadith and Fiqh.