elk-reasoner/src/main/java/org/semanticweb/elk/reasoner/stages/AbstractReasonerStage.java
boolean invalidate() {
		if (!isCompleted_ && !isInitialized_) {
			return false;
		}
		LOGGER_.trace("{}: invalidated", this);
		isCompleted_ = false;
		isInitialized_ = false;
		return true;
	}
boolean invalidate() {
		if (!isCompleted_ && !isInitialized_) {
			return false;
		}
		LOGGER_.trace("{}: invalidated", this);
		isCompleted_ = false;
		isInitialized_ = false;
		return true;
	}
Marks this {@link AbstractReasonerStage} as not completed; this will
require its execution next time unless {@link #setCompleted()} is called

@return {@code true} if this stage was not invalidated and {@code false}
if this stage was already invalidated before the call