Premise:
"According to legend, it was originally named Mons Martyrum ' where, after being decapitated, the town's first bishop, Saint Denis, picked up his head and walked away."
Hypothesis: Saint Denis had been executed for proselytizing the Christian faith.

it is not possible to tell

Premise:
"Jon closed his eyes and enjoyed the comfortable warmth of the high red sun that had burned him so often."
Hypothesis: It was midnight, foggy, cold and dark.

no

Premise:
"When a system involving software is being developed, one or more cost models may be useful."
Hypothesis: When a system involving software is being developed, there could be more than one model that is useful.
yes