  Particle swaps can drastically accelerate dynamics in glass. The mechanism is
expected to be vital for a fundamental understanding of glassy dynamics. To
extract defining features, we propose a partial swappability with a fraction
{\phi_s} of swap-initiating particles, which can only swap locally with each
other or with regular particles. We focus on the swap-dominating regime. At all
temperatures studied, particle diffusion coefficients scale with {\phi_s} in
unexpected power laws with temperature-dependent exponents, consistent with the
kinetic picture of glass transition. At small {\phi_s}, swap-initiators,
becoming defect particles, induce remarkably typical glassy dynamics of regular
particles. This supports defect models of glass.
