I generally try to avoid expressions with ng-show and ng-hide as they were designed as booleans, not conditionals. If I need both conditional and boolean logic, I prefer to put in the conditional logic using ng-if as the first check, then add in an additional check for the boolean logic with ng-show and ng-hide
Howerver, if you want to use a conditional for ng-show or ng-hide, here is a link with some examples: Conditional Display using ng-if, ng-show, ng-hide, ng-include, ng-switch