Uncertainty propagation is the quantification of uncertainties in system output(s) propagated from uncertain inputs. His art plans remained vague and his future uncertain. This however meant basing knowledge upon something uncertain, and irrational. The Pachycormidae have a somewhat uncertain position. Invention is often an exploratory process with an uncertain or unknown outcome. Heuristics involve mental shortcuts which provide swift estimates about the possibility of uncertain occurrences. Others sign themselves to seek God's blessing before or during an event with uncertain outcome. This left the fate of "I-401" uncertain. The play closes with the family leaving for their new home but uncertain future. Ultimately, she enters the van with her future uncertain. XXXX collapses, contemplating his uncertain fate. However, legal disputes made the amount of any payment uncertain. The signs are classified as uncertain or certain signs. Morrison died in uncertain circumstances in 1971. Dwayne's plotlines often deal with his problems with girls, bullies and his uncertain future.