(a) the invention claimed in a patent cannot be exploited in the country without infringing a patent granted on the basis of an application benefiting from an earlier filing or where appropriate, priority date, and (b) where the invention claimed in the later patent involves an important technical advance of considerable economic importance in relation to the invention claimed in the earlier patent, the court, upon the request of the owner of the later patent, may issue a non-voluntary licence to the extent necessary to avoid infringement of the earlier patent. (6) Where a non-voluntary licence is issued under subsection (5), the court, upon the request of the owner of the earlier patent, shall issue a non-voluntary licence in respect of the later patent. (7) In the case of a request for the issuance of a non-voluntary licence under subsections (5) and (6), subsection (3) shall apply with such modifications as are necessary with the proviso that no time limit needs to be specified. (8) In the case of a non-voluntary licence issued under subsection (5), the transfer may be made only with the later patent, or, in the case of a non-voluntary licence issued under subsection (6), only with the earlier patent. (9) The request for the issuance of a non-voluntary licence is subject to payment of the prescribed fee. (10) Section 13(4) to (13) shall apply with such modifications as are necessary. Section 15—Invalidation. (1) An interested person may request the court to invalidate a patent. (2) The court shall invalidate the patent (a) if the person requesting the invalidation proves that a person has not complied with any of the requirements of sections 1(2) and (3), 2, 3, 5 (5), (6), (7) or (8); or (b) if the owner of the patent is not the inventor or the inventor's successor in title. (3) An invalidated patent, or claim or part of a claim, shall be regarded as null and void from the date of the grant of the patent. (4) The registrar of the court shall notify the Registrar of the final decision of the Court. (5) The Registrar shall record the decision and publish a reference of it in the prescribed manner.