spencer bloch, influenced by gersten's work on sheaves of "k"-groups, proved that on a regular surface, the cohomology group formula_11 is isomorphic to the chow group "ch"("x") of codimension 2 cycles on "x". inspired by this, gersten conjectured that for a regular local ring "r" with fraction field "f", "k"("r") injects into "k"("f") for all "n". soon quillen proved that this is true when "r" contains a field, and using this he proved that formula_12 for all "p". this is known as "bloch's formula". while progress has been made on gersten's conjecture since then, the general case remains open.