  In 2013 Andriy V. Bondarenko showed how to construct a two-distance
counterexample to Borsuk's conjecture from any strongly regular graph whose
vertex set is not the union of at most $f+1$ cliques (sets of pairwise adjacent
vertices) where $f$ is the multiplicity of the second-largest eigenvalue of its
adjacency matrix.
  He applied that construction to those two graphs that he had been able to
prove to fulfill the condition: From the $G_2(4)$ graph (on 416 vertices) he
got a 65-dimensional two-distance counterexample. From the $Fi_{23}$ graph (on
31671 vertices) he got a 782-dimensional one and, by considering certain
induced subgraphs, counterexamples in dimensions 781, 780 and 779.
  This article presents two other strongly regular graphs fulfilling the
condition, on 28431 and on 2401, resp., vertices. It gives dedicated
counterexamples in dimensions from 781 down to 764 derived from the bigger
graph (that turned out to be an induced subgraph of the $Fi_{23}$ graph) and a
240-dimensional counterexample derived from the smaller graph.
  Several contained propositions rely on the results of (often extensive)
computations, mainly within the computer algebra system GAP. The source package
contains (almost) all used source files.
