DIFFICULTY... This was a design problem but it became a project management exercise. The solution space is essentially infinite even with coarse sampling on the variables, so pursuing promising ideas without getting lost in the noise is the challenge. As the better design forms began to take shape they took progressively longer to reoptimize after changes until the clock ran down. INSIGHTS... I have been involved in new product development for most of my career and it is said in this field that the first person to touch a project designs in 75% of the cost. Which is another way of saying that starting assumptions can make or break you. I thought about the problem for awhile before starting on the computer and decided on a plan and worked toward that end throughout the time allowed. I started with the following assumptions: the first and last elements would be the highest index possible and there would layers of the lowest index materials as stand-ins for air. I was tempted to start with SF59 and LASF35, one or both, as bookends for the design, but felt that a European or Japanese designer could argue that a design containing these glasses wouldn't be legal there and I didn't want a good design to end up an asterisk in the end - nice but not legal. So, I used SF57 and LASFN31 or their equivalents. As for a number of elements, I assumed a very good lens meeting the criteria of the problem, but allowing for air spaces would probably contain 14 to 22 elements, based on simple survey of f1.8 35 mm camera lenses. I scaled the number of elements by the index change 1.5:1, confining my search to 21 to 33 element systems. By not fixing the element count the IODC eliminated the powerful global search algorithms of today's software, which was a good idea. I did not start with patent prescriptions (I would have, if I had your program). Sub-assemblies of reasonable glasses were created in forms corresponding to the major elements of telephoto, inverse telephoto, and symmetrical systems. A matrix was created for a process of substitution and position order which was refined during the course of the design. The glass substitution algorithm in the software became less effective after the designs took near final form and was not used past about midpoint. I never had any luck removing the low index materials, the design always turned to mud without a goodly number of them. The issue was where, how many, and balanced with what. I didn't run out of ideas, but time. The insight? Plan the work, work the plan COMMENTS... My design form submitted as C, is all Schott. The other 2, A and B contain Sumita glasses in addition to Schott and differ by f-number definition, in case of a dispute over the problem statement. My original intention was to simplify the problem using Shannon's 15 glass portfolio, and for most of the exercise that was true. I only substituted out of that small catalog at about midpoint. These design forms end up being called something, and I offer the following suggestion, "come to bed, honey" Thanks for the opportunity to participate.