The rules that use the category "<np-gapsout_null-gapsin_null-wh-sing>" are:

<user_dialog_command-command>

<np-gapsout_null-gapsin_null-wh-sing> <existence_claim-sing-inv-gapsout_null-gapsin_np_gap>

<user_dialog_command-user_response>

<np-gapsout_null-gapsin_null-wh-sing> <existence_claim-sing-inv-gapsout_null-gapsin_np_gap>