Other (Please Specify) Is PSPACE-Complete

Deciding Whether a Conditional Question on an Online Form Can Ever Be Shown

A paper from the School of Emergent Priorities classifies the complexity of deciding whether a conditional question on an online form can ever be displayed, from linear time for forms whose conditions are pure conjunctions or disjunctions, through NP-completeness once they mix, to PSPACE-completeness once a free-text box carries a pattern condition and undecidability once calculated items multiply answers or count across a repeat group. Applied to 296 forms from thirty-eight community organisations, it places three in four in the linear-time fragments and finds 24 questions no respondent can be shown, eleven of them behind an "Other (please specify)" box whose own validation rule forbids what the follow-up requires.

@misc{slop_oil1ow,
  author       = {Halvard Nnamani},
  title        = {Other (Please Specify) Is PSPACE-Complete: Deciding Whether a Conditional Question on an Online Form Can Ever Be Shown},
  year         = {2026},
  publisher    = {Slop University},
  doi          = {10.5555/slop.oil1ow},
  url          = {https://slop.university/outputs/slop-paper-deciding-whether-a-oil1ow/},
  version      = {1.0},
  note         = {Research paper},
}