EPSO Abstract Reasoning flashcards
EPSO Abstract Reasoning · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Modular position cycle
- An element moving k steps per frame in an n-frame cycle returns to its start after n/gcd(n,k) frames. A 4-frame cycle with step 2 repeats every 2 frames.
- Alternating series split
- When two rules interleave, separate odd-numbered and even-numbered frames and analyse each subsequence independently. Each subsequence usually follows a simple constant rule.
- Bouncing element rule
- An element reflecting at a boundary shows alternating +k and −k steps. The underlying speed is constant; only the direction sign flips at the edge.
- Constant-step rotation
- Measure the angle between consecutive orientations. Common steps are 45°, 90°, and 135° clockwise; the step itself may increase by a fixed increment each frame.
- Chirality test
- Rotation preserves handedness; reflection reverses it. If an asymmetric figure appears mirrored rather than turned, the transformation is a reflection, not a rotation.
- Fixed-vector translation
- Grid position moves by a constant row and column delta each frame. Track row and column changes separately, since diagonal moves change both by equal magnitudes.
- XOR overlay rule
- Lines present in exactly one of two overlaid figures survive; lines present in both are cancelled. Shading follows the same exclusive-or logic per region.
- Row-column consistency
- A valid matrix rule must hold for every complete row and every complete column. A candidate satisfying only the row is a distractor.
- Attribute decomposition
- Break each matrix cell into attributes (side count, shading, orientation, dot count). Each attribute may follow a different row or column rule.
- Odd-one-out uniqueness
- The intended rule must isolate exactly one figure. A rule splitting the set 4-2 or 3-3 is invalid; test attributes until one produces a single outlier.
- Enclosed-region count
- Count closed areas inside a figure, ignoring the outer boundary. Euler's formula V − E + F = 2 gives enclosed regions as F − 1 for connected planar figures.
- Convex versus concave
- A convex figure has every internal segment lying inside it; a concave figure has at least one indentation. This binary classifier often separates otherwise similar shapes.
- Analogy relation enumeration
- State the full transformation from A to B before examining options. Apply the identical transformation, in the same order, to C to obtain the answer.
- Multi-step analogy
- A to B may combine rotation and shading change. Apply the same composition in the same sequence to C; partial matches in options are distractors.
- Attribute mapping analogy
- If A's outer shape becomes B's inner shape, then C's outer shape becomes the answer's inner shape. Mapping must be consistent across all attributes.
- Union overlay rule
- All lines from both figures appear in the result. Overlapping lines are drawn once and remain visible; nothing is removed.
- Intersection overlay rule
- Only lines common to both figures survive; lines unique to either figure disappear. The result is the shared skeleton of the two inputs.
- XOR segment count check
- Surviving segments equal segments in A plus segments in B minus twice the shared segments. Use this arithmetic to verify a candidate answer.
- Rotation order
- The order of a rotation is how many applications return the figure to start: 90° has order 4, 180° order 2, 120° order 3, 45° order 8.
- Composition of two reflections
- Reflection in line L followed by reflection in line M equals a rotation by twice the angle between L and M, about their intersection point.
- Symmetry axes of regular polygon
- A regular n-gon has n symmetry axes: through each vertex and opposite midpoint when n is odd; alternating vertex-vertex and edge-midpoint axes when n is even.
- Dihedral versus cyclic symmetry
- A figure with n mirror axes and rotational order n has dihedral symmetry D_n. Rotation without mirror symmetry is cyclic C_n and the figure is chiral.
- Euler planar formula
- For a connected planar figure, V − E + F = 2, where F includes the outer face. Enclosed regions equal F − 1.
- Polygon diagonal count
- An n-sided polygon has n(n − 3)/2 diagonals. A hexagon has 9; an octagon has 20. Use this to distinguish similar-looking polygons by line count.
- Maximum line intersections
- n straight lines in general position produce at most n(n − 1)/2 intersection points. Each new line adds n − 1 crossings.
- Regions formed by lines
- n lines in general position divide the plane into n(n + 1)/2 + 1 regions. Three lines give 7 regions; four lines give 11.
- Interior angle of regular n-gon
- Each interior angle of a regular n-sided polygon equals (n − 2) × 180° / n. A regular hexagon has interior angles of 120°.
- Grid segment count
- In an m × n grid of unit cells, horizontal unit segments number m(n + 1) and vertical segments number n(m + 1). Count all lengths separately.
- Superposition count verification
- After applying an overlay rule, count surviving elements and compare with the arithmetic prediction from the two input figures to catch errors.
- Fibonacci-like count series
- A count series where each term equals the sum of the two preceding terms. Test this when differences are not constant and ratios are not constant.
- Anchor element method
- A fixed marker (corner dot, border) does not move across frames. Measure other elements' displacement relative to it to get absolute rather than relative motion.
- Diagonal reflection swap
- Reflection across the line y = x swaps coordinates (x, y) to (y, x). This equals a 90° rotation composed with a horizontal reflection.