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this needs to be improved and developed in line with little manual.html, especially and together with the section an abstract logic

the world is more than just a collection of facts

in the following

A, B, C, … are facts

AB is the compound fact, A and B, that both obtain (alternative notations are A.B and AÙB)

ABC…F is the compound fact A and B and C … and F that all A, B, C, … and F obtain

AÚB is the compound fact, A or B, that at least one of A and B obtain (here, ‘or’ is the inclusive or which contrasts to the exclusive sense in which just one of A and B obtain)

AÚBÚC … ÚF is the compound fact that at least one of A, B, C, … and F obtain

the following are inferences

A obtains and B obtains ® AB obtains (usually read ‘A and B imply AB’)

at least one of A and B obtains ® AÚB obtains