Methods, computing systems and computer program products implement embodiments of the present invention that include identifying a set of the items in the transactions, and executing, using input including the transactions, an implicit feedback collaborative filtering model to compute, for each of the users, a predicted rating for each of the items. Using input including the transactions and the predicted ratings as labels, a sentiment analysis model is executed to compute, for each given user, an opinion for each of the given items in the transactions for the given user, and using input including the transactions and the opinions as factors for the predicted ratings, an explicit feedback collaborative analysis model is executed to update, for each of the users, the predicted ratings for each of the items.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A method, comprising: receiving a set of transactions for multiple users, each of the transactions comprising a user, an item, and a text string indicating an attitude of the given user toward the item; identifying a set of the items in the transactions; executing, using input comprising the transactions, an implicit feedback collaborative filtering model to compute, for each of the users, a predicted rating for each of the items; executing, using input comprising the transactions and the predicted ratings as labels, a sentiment analysis model to compute, for each given user, an opinion for each of the given items in the transactions for the given user; and executing, using input comprising the transactions and the opinions as factors for the predicted ratings, an explicit feedback collaborative analysis model to update, for each of the users, the predicted ratings for each of the items. 2. The method according to claim 1, wherein using the predicted ratings as the labels trains the sentiment analysis model, and wherein using the opinions as factors trains the explicit collaborative feedback model. 3. The method according to claim 2, and further comprising repeating the steps of executing the sentiment analysis model and executing the explicit feedback collaborative filtering model until the opinions and the predicted ratings reach respective stable states. 4. The method according to claim 2, wherein the transactions comprise first transactions, wherein the users comprise first users, wherein the items comprise first items, wherein the text strings comprise first text strings, wherein the opinions comprise first opinions, and further comprising receiving second transactions for a second user and a request for second opinions, each of the second transactions comprising the second user, a second item, and a second text string indicating an attitude of the second user about the second item, and executing, using input comprising the second transactions, the trained sentiment analysis model to compute, in response to the request, a second opinion for each of the second items in the second transactions for the second user. 5. The method according to claim 2, wherein the transactions comprise first transactions, wherein the users comprise first users, wherein the items comprise first items, wherein the text strings comprise first text strings, wherein the predicted ratings comprise first predicted ratings, and further comprising receiving second transactions for a second user and a request for second predicted ratings, each of the second transactions comprising the second user, a second item, and a second text string indicating an attitude of the second user about the second item, and executing, using input comprising the second transactions, the trained explicit feedback collaborative analysis model to compute, in response to the request, respective second predicted ratings for each of the second items in the second transactions for the second user. 6. The method according to claim 1, and further comprising skipping the performing of the implicit feedback collaborative filtering model, computing, using a transfer learning algorithm, the labels for each of the text strings, and conveying the labels to the sentiment analysis. 7. An apparatus, comprising: a memory configured to store an implicit feedback collaborative filtering model, a sentiment analysis model and an explicit feedback collaborative filtering model; and a processor configured to: to receive a set of transactions for multiple users, each of the transactions comprising a user, an item, and a text string indicating an attitude of the user toward the item, to identify a set of the items in the transactions, to execute, using input comprising the transactions, the implicit feedback collaborative filtering model to compute, for each of the users, a predicted rating for each of the items, to execute, using input comprising the transactions and the predicted ratings as labels, the sentiment analysis model to compute, for each given user, an opinion for each of the given items in the transactions for the given user, and to execute, using input comprising the transactions and the opinions as factors for the predicted ratings, the explicit feedback collaborative analysis model to update, for each of the users, the predicted ratings for each of the items. 8. The apparatus according to claim 7, wherein using the predicted ratings as the labels trains the sentiment analysis model, and wherein using the opinions as factors trains the explicit collaborative feedback model. 9. The apparatus according to claim 8, wherein the processor is further configured to repeat the steps of executing the sentiment analysis model and executing the explicit feedback collaborative filtering model until the opinions and the predicted ratings reach respective stable states. 10. The apparatus according to claim 8, wherein the transactions comprise first transactions, wherein the users comprise first users, wherein the items comprise first items, wherein the text strings comprise first text strings, wherein the opinions comprise first opinions, and wherein the processor is further configured to receive second transactions for a second user and a request for second opinions, each of the second transactions comprising the second user, a second item, and a second text string indicating an attitude of the second user about the second item, and to execute, using input comprising the second transactions, the trained sentiment analysis model to compute, in response to the request, a second opinion for each of the second items in the second transactions for the second user. 11. The apparatus according to claim 8, wherein the transactions comprise first transactions, wherein the users comprise first users, wherein the items comprise first items, wherein the text strings comprise first text strings, wherein the predicted ratings comprise first predicted ratings, and wherein the processor is further configured to receive second transactions for a second user and a request for second predicted ratings, each of the second transactions comprising the second user, a second item, and a second text string indicating an attitude of the second user about the second item, and to execute, using input comprising the second transactions, the trained explicit feedback collaborative analysis model to compute, in response to the request, respective second predicted ratings for each of the second items in the second transactions for the second user. 12. The apparatus according to claim 7, and wherein the processor is further configured to skip the performing of the implicit feedback collaborative filtering model, to compute, using a transfer learning algorithm, the labels for each of the text strings, and to convey the labels to the sentiment analysis. 13. A computer program product, the computer program product comprising: a non-transitory computer readable storage medium having computer readable program code embodied therewith, the computer readable program code comprising: computer readable program code configured to receive a set of transactions for multiple users, each of the transactions comprising a user, an item, and a text string indicating an attitude of the user toward the item; computer readable program code configured to identify a set of the items in the transactions; computer readable program code configured to execute, using input comprising the transactions, an implicit feedback collaborative filtering model to compute, for each of the users, a predicted rating for each of the items; computer readable program code configured to execute, using input comprising the transactions and the predicted ratings as labels, a sentiment analysis model to compute, for each given user, an opinion for each of the given items in the transactions for the given user; and computer readable program code configured to execute, using input comprising the transactions and the opinions as factors for the predicted ratings, an explicit feedback collaborative analysis model to update, for each of the users, the predicted ratings for each of the items. 14. The computer program product according to claim 13, wherein using the predicted ratings as the labels trains the sentiment analysis model, and wherein using the opinions as factors trains the explicit collaborative feedback model. 15. The computer program product according to claim 14, and further comprising computer readable program code configured to repeat the steps of executing the sentiment analysis model and executing the explicit feedback collaborative filtering model until the opinions and the predicted ratings reach respective stable states. 16. The computer program product according to claim 14, wherein the transactions comprise first transactions, wherein the users comprise first users, wherein the items comprise first items, wherein the text strings comprise first text strings, wherein the opinions comprise first opinions, and further comprising computer readable program code configured to receive second transactions for a second user and a request for second opinions, each of the second transactions comprising the second user, a second item, and a second text string indicating an attitude of the second user about the second item, and to execute, using input comprising the second transactions, the trained sentiment analysis model to compute, in response to the request, a second opinion for each of the second items in the second transactions for the second user. 17. The computer program product according to claim 14, wherein the transactions comprise first transactions, wherein the users comprise first users, wherein the items comprise first items, wherein the text strings comprise first text strings, wherein the predicted ratings comprise first predicted ratings, and further comprising computer readable program code configured to receive second transactions for a second user and a request for second predicted ratings, each of the second transactions comprising the second user, a second item, and a second text string indicating an attitude of the second user about the second item, and to execute, using input comprising the second transactions, the trained explicit feedback collaborative analysis model to compute, in response to the request, respective second predicted ratings for each of the given items in the second transactions for the second user. 18. The computer program product according to claim 13, and further comprising computer readable program code configured to skip the performing of the implicit feedback collaborative filtering model, to compute, using a transfer learning algorithm, the labels for each of the text strings, and to convey the labels to the sentiment analysis.