Invariably, when you write email with questions regarding logic problems, or when you post on the discussion board on Blackboard, you’ll want to use some of the logical symbols. In email, you will probably be best off using some plain-text approximation of these symbols. In BlackBoard, you can use “HTML4 character entity references” which will be displayed as the actuall symbols by any HTML4 compliant browser (that includes most recent versions of Internet Explorer, Netscape, Mozilla, Opera, Safari, etc.). Here’s a table of suggested plain-text approximations of symbols and HTML4 entity references.
| Symbol name | Symbol | Plain Text | HTML4 code | |||
|---|---|---|---|---|---|---|
| and | ∧ | ^ or & | ∧ | |||
| or | ∨ | v or | | ∨ | |||
| not | ¬ | ~ | ¬ | |||
| conditional | → | -> | → | |||
| biconditional | ↔ | <-> | ↔ | |||
| for all | ∀ | @ or A | ∀ | |||
| there exists | ∃ | / or E or 3 | ∃ | |||
| equal | = | = | = | |||
| non equal | ≠ | # or =/= | ≠ | |||
| less than or equal | ≤ | <= | ≤ | |||
| greater than or equal | ≥ | >= | ≥ | |||
| element of | ∈ | in | ∈ | |||
| not element of | ∉ | not in | ∉ | |||
| subset of | ⊆ | <= | ⊆ | |||
| union | ∪ | u | ∪ | |||
| intersection | ∩ | ^ | ∩ | |||
| powerset | ℘ | Pow | ℘ | |||
| infinity | ∞ | infinity | ∞ |
To get Greek letters, just put the name of the greek letter between ‘&’ and ‘;’. For instance, ‘Γ’ produces ‘?’, and ‘α’ produces ‘?’. In email, just write out the name of the letter.
To get subscripts and superscripts on BlackBoard, surround them by <sub>..</sub> or <sup>…</sup>. For instance, ‘x<sub>3</sub>’ produces ‘x2‘ and ‘2<sup>n</sup>’ produces ‘2n‘. In email, use underscore (_) and caret to indicate subscripts and superscripts (e.g., ‘x_3’ and ‘2^n’).