New upper bounds for 17 covering numbers C(v,k,t)

Explicit covering designs that improve the best known upper bounds for 17 covering numbers C(v,k,t), compared with the values listed on coveringrepository.com on 2026-10-26. A (v,k,t) covering design is a set of k-element subsets (blocks) of {1,...,v} such that every t-element subset lies in at least one block; C(v,k,t) is the smallest possible number of blocks. Each design file proves the stated upper bound. New bounds: C(41,6,3) <= 573, C(46,8,4) <= 3553, C(47,8,4) <= 3985, C(49,7,3) <= 652, C(49,7,4) <= 8802, C(52,7,3) <= 774, C(58,10,2) <= 42, C(61,8,3) <= 833, C(70,8,3) <= 1238, C(75,24,4) <= 208, C(76,23,4) <= 293, C(77,8,3) <= 1672, C(77,24,4) <= 236, C(83,23,4) <= 448, C(86,9,3) <= 1543, C(89,8,3) <= 2610, C(93,24,4) <= 436. The previous best values, their holders and dates are in README.md and results.tsv inside the archive. Run python3 verify.py to check every design exhaustively. The designs were found by seeded local search (simulated annealing and weighted local search) starting from the record designs of the final La Jolla Covering Repository snapshot (doi:10.5281/zenodo.10779736). Searches and verification were carried out with Claude (Anthropic) under the direction of Kerem Özdemir.