§ 920. Presumptions

In any proceeding for the enforcement of a claim for compensation under this chapter it shall be presumed, in the absence of substantial evidence to the contrary—

• (a) That the claim comes within the provisions of this chapter.
• (b) That sufficient notice of such claim has been given.
• (c) That the injury was not occasioned solely by the intoxication of the injured employee.
• (d) That the injury was not occasioned by the willful intention of the injured employee to injure or kill himself or another.