### Instruction:

Extract the cause and effect entities from the following sentence:
This start date is mandatory and, if no end date is communicated, then implies that the price is effective until further notice

### Assistant:

KEYWORD: then
NEGATION: no
VARIABLE: This start date
CONDITION: implies that the price is effective until further notice
NOT_RELEVANT: is mandatory and
EFFECT_1: implies that the price is effective until further notice
CAUSE_1: no end date is communicated

