相當因果關係的定義 The Definition of Reasonable Causality

因果關係係定義為若因則果，若且唯若，因之集合包含於果之集合。	A causality is defined, if and only if, a kind of causes results in a kind of effects, if and only if, the set of the effects is included in the set of the effects.
因果機率係定義為因之集合與果之集合之交集之基數除以因之集合之基數。	A causal probability is defined by the ratio of the cardinal number of the intersection of the set of the causes and the set of effects to the cardinal number of the set of the causes.
相當因果關係係定義為因之集合部分包含於果之集合而其因果機率超過相當閥值者。	A reasonable causality is defined, if and only if, the set of the effects is partially included in the set of the effects with a causal probability that exceeds a reasonable threshold.