Real-time product selection guidance for conditional sales

A computer program product comprising one or more non-transitory computer-readable storage devices, and program instructions stored on at least one of the one or more storage devices, the stored program instructions comprising program instructions for performing the steps:

• scanning a first physical product placed a physical shopping cart using a data processing apparatus coupled to the physical shopping cart, the physical shopping cart located in a physical store;
• identifying a product identifier of the scanned first physical product;
• querying a backend system with the product identifier, where the backend system stores, for each of a plurality of products in the physical store, a set of conditions that define a valid combination of products in the physical store;
• receiving, from the backend system in response to the querying, an identification of a second physical product in the physical store, where the first physical product and the second physical product are included in the valid combination of products in the physical store satisfying the set of conditions for the first physical product;
• obtaining a location of the second physical product in the physical store;
• and
• displaying information about the second physical product and information about the location of the second physical product in the physical store on a display device to a shopper using the shopping cart, the shopper being physically situated in the physical store.