1. A computer-implemented method for assisting a user of a content item, comprising: receiving, by a search expression generator operated by a computer system, the content item, wherein the content item is a selected one of a web page, a post to a social networking site, a post to a blog, a post to an online bulletin board, a document, or an electronic message, having text divisible into a plurality of subtexts; and generating a search expression, by the search expression generator, based on the content item, to search other content items, through execution of the search expression, wherein the search expression is to include a hierarchy of a plurality of nested juxtaposition sub-expressions corresponding with nesting of subtexts of the content item; wherein the search expression is to be applied by a search engine operated on the same or a different computer system, to the other content items to generate a search result; wherein generating comprises recursively dividing the text of the content item into the subtexts, and transforming the subtexts into the search sub-expressions; and wherein the content item is a first content item, and the search result includes a second content item to be recommended to the user.
1. A computer-implemented method for assisting a user of a content item, comprising: receiving, by a search expression generator operated by a computer system, the content item, wherein the content item is a selected one of a web page, a post to a social networking site, a post to a blog, a post to an online bulletin board, a document, or an electronic message, having text divisible into a plurality of subtexts; and generating a search expression, by the search expression generator, based on the content item, to search other content items, through execution of the search expression, wherein the search expression is to include a hierarchy of a plurality of nested juxtaposition sub-expressions corresponding with nesting of subtexts of the content item; wherein the search expression is to be applied by a search engine operated on the same or a different computer system, to the other content items to generate a search result; wherein generating comprises recursively dividing the text of the content item into the subtexts, and transforming the subtexts into the search sub-expressions; and wherein the content item is a first content item, and the search result includes a second content item to be recommended to the user. 6. The method of claim 1 , wherein the search expression is a first search expression; the other content items are first other content items; the user also uses a second content item, and the method further comprises: receiving, by the search expression generator, a constituent of the second content item, wherein the second content item is also a selected one of a web page, a post to a social networking site, a post to a blog, a post to an online bulletin board, a document, an electronic message, a product description, an entertainment description, or an advertisement, having text divisible into a plurality of subtexts; and generating a second search expression, by the search expression generator, based on the constituent of the second content item, to search second other content items, through execution of the second search expression, wherein the second search expression includes a hierarchy of a plurality of nested juxtaposition sub-expressions corresponds with nesting of subtexts of the constituent of the second content item; wherein the second search expression is to be applied by the search engine operated on the same or a different computer system, to the second other content items to generate a second search result.