1) At any time within four months from the date of advertisement of the acceptance of a complete specification under this Act (or within such further period not exceeding one month in the aggregate as the Controller may allow on application made to him in the prescribed manner before the expiry of the four months aforesaid) any person interested may give notice to the Controller of opposition to the grant of the patent on any of the following grounds,namely: a.that the applicant for the patent or the person under or through whom he claims,wrongfully obtained the invention or any part thereof from him or from a person under or through whom he claims; b.that the invention so far as claimed in any claim of the complete specification has been published before the priority date of the claim i.in any specification filed in pursuance of an application for a patent made in India on or after the 1st day of January,1912; or ii.in India or elsewhere,in any other document: Provided that the ground specified in Sub-cl.(ii) shall not be available where such publication does not constitute an anticipation of the invention by virtue of Sub-s.(2) or Sub-s.(3) of Section 29; that the invention so far as claimed in any claim of the complete specification is claimed in a claim of a complete specification published on or after the priority date of the applicant's claim and filed in pursuance of an application for a patent in India,being a claim of which the priority date is earlier than that of the applicant's claim; a.that the invention so far as claimed in any claim of the complete specification was publicly known or publicly used in India before the priority date of that claim