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  2. Quasicrystal - Wikipedia

    en.wikipedia.org/wiki/Quasicrystal

    The more precise mathematical definition is that there is never translational symmetry in more than n – 1 linearly independent directions, where n is the dimension of the space filled, e.g., the three-dimensional tiling displayed in a quasicrystal may have translational symmetry in two directions.

  3. AP Biology - Wikipedia

    en.wikipedia.org/wiki/AP_Biology

    Advanced Placement (AP) Biology (also known as AP Bio) is an Advanced Placement biology course and exam offered by the College Board in the United States. For the 2012–2013 school year, the College Board unveiled a new curriculum with a greater focus on "scientific practices".

  4. List of aperiodic sets of tiles - Wikipedia

    en.wikipedia.org/wiki/List_of_aperiodic_sets_of...

    A tiling that cannot be constructed from a single primitive cell is called nonperiodic. If a given set of tiles allows only nonperiodic tilings, then this set of tiles is called aperiodic . [ 3 ] The tilings obtained from an aperiodic set of tiles are often called aperiodic tilings , though strictly speaking it is the tiles themselves that are ...

  5. Advanced Placement exams - Wikipedia

    en.wikipedia.org/wiki/Advanced_Placement_exams

    Advanced Placement (AP) examinations are exams offered in United States by the College Board and are taken each May by students. The tests are the culmination of year-long Advanced Placement (AP) courses, which are typically offered at the high school level. AP exams (with few exceptions [1]) have a multiple-choice section and a free-response ...

  6. Einstein problem - Wikipedia

    en.wikipedia.org/wiki/Einstein_problem

    In plane geometry, the einstein problem asks about the existence of a single prototile that by itself forms an aperiodic set of prototiles; that is, a shape that can tessellate space but only in a nonperiodic way. Such a shape is called an einstein, a word play on ein Stein, German for "one stone". [2]

  7. Aperiodic tiling - Wikipedia

    en.wikipedia.org/wiki/Aperiodic_tiling

    An aperiodic tiling is a non-periodic tiling with the additional property that it does not contain arbitrarily large periodic regions or patches. A set of tile-types (or prototiles) is aperiodic if copies of these tiles can form only non-periodic tilings. The Penrose tilings are a well-known example of aperiodic tilings. [1] [2]

  8. College Level Examination Program - Wikipedia

    en.wikipedia.org/wiki/College_Level_Examination...

    The main difference between the two is that CLEP programs are designed to be taken without enrolling in classes, while AP exams are normally taken after completing an AP course. [13] AP exams are graded in 5 grades, while CLEP exams has a score range of 20 to 80, with 50 being the recommended minimum passing score. [14] There is an upper age ...

  9. Aperiodic crystal - Wikipedia

    en.wikipedia.org/wiki/Aperiodic_crystal

    The history of aperiodic crystals can be traced back to the early 20th century, when the science of X-ray crystallography was in its infancy. At that time, it was generally accepted that the ground state of matter was always an ideal crystal with three-dimensional space group symmetry, or lattice periodicity.